1.0 Installing the Comscope Unit

The Comscope unit simply plugs into one of the printer ports on your PC. Plug the 25 pin 'D' connector into the 25 pin 'D' connector on your PC.
The Comscope software will automatically find which printer port the Comscope is connected to (as long as the unit is turned on.) However, the Comscope software will load slightly faster if you save a new default configuration (see 5.2 below.) Simply go to the HARDWARE menu and hit ENTER to save the address the Comscope software has identified.
You may need to set the mode of your PC's printer port to operate properly with the Comscope. You will need to consult your PC's manual for details on how to do this, since each PC is different. Typically, your PC will display a message like "Hit F1 or Delete for setup" when it is first booting up. The BIOS setup screen will include an option for setting the mode of your printer port. Set the printer port for 'EPP' (Enhanced Parallel Port) if possible, or 'Compatibility mode' if not. The Comscope will not work with 'ECP' mode.

1.1 Installing the Software
Make a copy of the distribution diskette. If you will be running the Comscope from a hard disk then we recommend that you create a separate directory and copy all files from the disk to this directory.
There are three programs on the distribution diskette: CGA.exe, EGA.exe, and MONO.exe. The CGA program will run on CGA, EGA, or VGA displays and uses the 320 x 200 graphics mode for data display. The EGA program will run on EGA or VGA displays and uses the soft font mode for data display. The EGA display shows more data and is somewhat faster. The MONOchrome program is intended for monochrome displays but will also work on color.

1. To make a working copy of the diskette:

• insert diskette in drive a:
  
• insert a blank diskette in drive b: if you have one, or follow DOS prompts to insert blank disk in a:
  
• enter DISKCOPY A: B: at the DOS prompt

2. To install programs on a hard disk:

• make hard disk current disk
  

  e.g. enter C: at the DOS prompt

• create the directory for the Comscope programs:
  

  enter MD 905 at the DOS prompt
  enter CD 905 at the DOS prompt

• Insert the working copy of the diskette in drive a:
  

  enter COPY A: *.* at the DOS prompt

3. Copy the program for the adapter you are using (CGA, EGA, or Monochrome) to a file named OM.EXE

enter:


COPY CGA.EXE OM.EXE at the DOS prompt or
COPY EGA.EXE OM.EXE or
COPY MONO.EXE OM.EXE

4. Type OM at the DOS prompt to start the program.

You may also automatically start an application by entering the name (without the .OM4 extension) after OM:

enter OM APP_NAME at the DOS prompt

The Comscope will search for APP_NAME.OM4 in the current directory and start it if found.

There are five types of files that the Comscope will look for or create in the current working directory:

CONFIG.OM3: This file contains the hardware address of the Comscope board, the default monitoring mode, the default print setting, and the screen color.

xxxxxx. OM1: files with an .OM1 extension are files of captured data (or 'journal' files.) You may examine the data by selecting a file from the EXAMINE FILE menu (Section 5.4.)

xxxxxx. OM2: files with an .OM2 extension are configuration files. You may have several predefined operating modes that may be selected from the CANNED CONFIGURATION menu (Section 5.2.)

xxxxxx. OM5: files with an .OM5 extension are display code translation files. The names appear in the code menus of the mode submenus (e.g. Section 7.6.)

xxxxxx. OM4: files with an .OM4 extension are executable application programs. These programs are selected via the PROGRAM OPTION menu (Section 5.3.)

xxxxxx. OM8: These are the program files for the co-processor in the Comscope unit.

2.0 The Electrical Interfaces

The Comscope directly supports the RS-232, V.35, EIA 530 (RS-422), and RS-485 electrical interfaces. Special cables provide the physical connection between the Comscope and the circuit under test. The Comscope can passively monitor single ended signals like RS-232 in the range of +/- 5 to 15 Volts, or differential signals like RS-422. The Comscope automatically handles either type of signal - you do not need to set or select anything to passively monitor the different electrical interfaces. The Comscope can also emulate either a DTE or DCE in RS-232, V.35, EIA 530, or RS-485. The emulate mode is software selected. See Section 16.0.

The following tables list the signals supported by the Comscope. An 'x' shows those pins that are driven by the Comscope when emulating a DTE or DCE.

RS-232:

V.35

EIA 530 (RS-422)

RS-485 mode is the same as EIA 530, except that in asynchronous mode the transmitter (TxD or RxD) is turned on when data is transmitted and turned off when the data is fully transmitted. This allows you to emulate 2 wire half-duplex protocols.
The Comscope is shipped with a 'T' cable for tapping into the circuit you are testing. One leg of the 'T' cable plugs into the 25 pin 'D' connector on the rear of the Comscope unit. The data line cable must be disconnected and both ends plugged into the 'T' cable. For instance, you would remove the cable from a modem and then plug the cable and the modem into two connectors on the 'T' cable. The Comscope can then capture and display the activity on the data line.

3.0 Using the Comscope

3.1 Navigating the menus
The Comscope program has been designed to be as self-explanatory as possible without obstructing the experienced user. You select the various operating modes from menus. Each menu screen has a list of key words across the top. You 'pull down' the menu associated with the key words by using the left and right arrow keys at the right of your keyboard. Make sure the 'Num Lock' key is not on. The up and down keys select the particular option within each pull down menu. The selected option is highlighted with a green bar and the cursor will be flashing at the right of the selection. Some menu options allow you to enter a value, such as a Baud rate. Options of this type are prefaced by a ">." Use the up or down arrow key to move the green bar to the "> " then enter the appropriate value from the keyboard. Each menu screen will also list several function keys, which are the F1 through F10 keys along the left side or top of your keyboard. Depressing the appropriate key will immediately execute the indicated action, such as quitting the program (F10.)
The bottom line of each menu screen is the explanation line, which gives a brief description of what each menu means. The line directly above this, which is usually blank, is the error line. If an error occurs, such as entering a file name that is not valid, then an error message will be displayed on this line, which will be accompanied by a beep from the speaker. The ENTER, or RETURN key is used as an 'execute' command. This key is used in several menus throughout the program. The explanation line at the bottom of the screen will indicate the action of the ENTER key for those menus.

3.2 Viewing data line activity
You will likely use the Comscope most often to view activity on a data line. In 'live mode' the Comscope captures data line activity and displays it on the screen as it is happening.
'Capture' means that the Comscope is actually keeping an internal history of that activity, so that you can stop monitoring and look back through the data, in 'review mode.' You may also store this history in a file called a journal file. The data can then be examined at another time and even by another PC. This also allows you to save more data line history than the Comscope can hold in memory. The Comscope can store 64 KBYTES of data, without journalling, before the data is overwritten by new data.
In order to view data line activity you must tell the Comscope what type of data is on the data line. Do this by selecting the mode from the main menu and the parameters within that mode from the individual mode submenus. Once you have selected a data mode, you can save it to a named configuration file for later use or as the configuration the Comscope will default to when first started. The selected mode also identifies the type of data an application program will generate, unless the application program overrides the selected mode. The Comscope does a minimal amount of interpretation of data. It assembles individual bits into characters and identifies certain low level error conditions. In the synchronous protocols, the Comscope delineates data blocks as well. Higher level analysis of line data is accomplished with application programs.

3.3 Setting search sequences
The Comscope provides a powerful aid in looking for specific data line occurrences. You can use the Search Menu to identify certain sequences of events. You can direct the Comscope to highlight data or to freeze the display when the sequence occurs. The Search Menu is also useful in searching through captured data.

3.4 Running an application program
The Comscope includes an Application Program Interface (API) that allows application programs to extend the capabilities of the Comscope. These programs can analyze and generate line data, allowing protocol decode, emulation's, error rate analysis, and more. These application routines must include their own documentation to explain their use. Two programs are included with the Comscope, 'Fox' and 'Term'. Their use is explained in Section 19.
The following sections describe the various menus and what they mean. You may find it helpful to step through the program on your computer as you read the following sections.

4.0 Main Menu Function Keys

4.1 F3 - Review Captured Date
If no application program has been selected, depressing function key F3 will put the Comscope in review mode (Section 13.0), allowing you to review captured data line activity. Captured data remains in memory until overwritten by new data.
Shift F3 Depressing the Shift key and F3 simultaneously will deselect any application routine and enter review mode. Application programs must be de-selected before reviewing captured data.

4.2 Shift F4 - Print Captured Data
Depressing the Shift key and function key F4 simultaneously will bring up the Print menu, which allows you to print a copy of data in the capture buffer. See Section 14.

4.3 F5 - Save Current Configuration
You may generate a named copy of the currently selected configuration for future use as described in Section 5.2 below. Depressing function key F5 will cause a box to appear in the center of the screen. Enter the name you want the configuration saved under. If you enter the name of a configuration that already exists the previous configuration will be overwritten. Do not use any extension (no'.') in the name. The Comscope will save the configuration in a file with the name you selected and the extension "OM2."

4.4 F6 - Define A Search Sequence
The Comscope allows you to set up a sequence of events that it will search for. The sequence may be searched for in live data line activity or in captured data. The search facility may also be used by an application program. Depressing function key F6 will bring up the search menu where the sequence can be set up. See Section 11.

4.5 F7 - Toggle Control Lead Capture
When control lead capture is ON the Comscope will capture all control lead changes as well as displaying them. If control lead capture is OFF the Comscope will display the state of the leads but not capture them, so that control lead changes will not show in a journal file or when Reviewing Captured Data. The control leads are displayed at the lower left of the screen. Inverse video (black letters in a white box) indicates that the control lead is 'on.' while normal video indicates that the lead is 'off' (see Section 2.0). NOTE: There are situations where noise on unused control leads can consume excessive processor time and buffer space and control lead capture must be OFF. Depressing F7 will switch control lead capture ON and OFF as shown to the right of the F7 prompt at the lower middle of the screen.

4.6 F8 - Toggle Time Stamping
When time stamping is enabled, the Comscope will place time stamps in the capture buffer. The time (to 1/100 seconds) will be displayed in the lower right corner of the data screen when in captured mode. Time stamping is given a lower priority than displaying data so that at higher data rates the time stamps may be rather infrequent.
Time stamping can quadruple the size of the real time buffer so you may wish to turn it off when journalling data.
Depressing F8 will switch time stamping ON and OFF as displayed to the right of the F8 prompt at the lower right of the screen.

4.7 F9 - View Data Line Activity
If no application program has been selected (Section 5.3) depressing function key F9 will cause the Comscope to immediately enter live mode to display data line activity (see Section 12).
If an application program has been selected it will be started, with the application directly accessing the serial data line.
Shift - F9 Depressing the Shift key and F9 simultaneously will de-select any application routines and cause the Comscope to enter live mode.

4.8 F10 - Exit Program
Depressing F10 will exit the Comscope program and return control to DOS. This key has this function at all times in the program.

5.0 Main Menu
This screen is entered when the program is first started. You will be in the MODE menu (see Section 5.1 below) when the program starts. This screen has six pull down menus: PROGRAM OPTION, CANNED CONFIGURATION, MODE, HARDWARE ADDRESS, EXAMINE FILE, INTERFACE, and eight function keys, described in Section 4.0.

5.1 Mode
This mode identifies the type of data that is to be monitored or generated: ASYNCHRONOUS, SYNCHRONOUS, HDLC, or UNKNOWN. These modes are described further under the individual submenu for the selected mode.

5.2 Canned Configuration:
The Comscope allows you to have a number of pre-defined named operating modes. These configurations are stored in files names xxxxxx. OM2, where xxxxxx is the file name displayed in this menu. These configurations are generated by depressing function key F5 (Sections 4.3 and 6.4.) The Comscope only displays the configurations found in the current directory. You may also select the ">" option and enter the DOS path name of a configuration file not shown. Do not enter the "OM2" extension.
Depressing function key F9 will load the highlighted configuration and immediately start monitoring or running the selected application program. If you wish to view or change the configuration before monitoring depress ENTER. Depressing the ENTER key will load the configuration and take you to the appropriate submenu.

5.3 Program Option
This menu lists the application programs found in the current directory. Application programs are named xxxxxx. OM4, where xxxxxx is the name displayed in this menu. You may also select the "> " option and enter the DOS path name of an application program not shown. Do not enter the ".OM4" extension. You can also enter the full name (with extension of an application program.) CAUTION: This option will allow you to run any file whether it is a legitimate executable program or not, which may lock up your system or worse.

Once an application routine has been selected, it will replace the normal live or captured mode functions. The application program is started:

1. By hitting function key F9 (Section 4.7.) In this case, the application routine is dealing with live data from and/or to the serial data line.

2. By hitting function key F3 (Section 4.1.) In this case, the application will be receiving data that has previously been captured.

3. By selecting a file from the EXAMINE FILE menu (Section 5.4.) In this case, the application will be receiving data from the selected file.

The source of the data is almost completely transparent to the application. A protocol decode program, for instance, can decode live data or data previously journalled to a file.

5.4 Examine File
This menu lists files of journalled data found in the current directory. Journalled data is stored in files named xxxxxx. OM1, where xxxxxx is the name displayed in this menu. You may also select the ">" option and enter the DOS path name of a file not shown. Do not enter the ". OM1" extension. These files are created by selecting the JOURNAL option from the mode submenus (Sections 7.7, 8.11, 9.7, and 10.7).
If an application program has been selected (Section 5.3), it will process data from the selected file. Not all applications will give meaningful results in this mode. If no application program has been selected you will be able to view the data in captured mode (Section 13.0).
Depressing the ENTER key will cause the Comscope to display a pseudo menu which displays the options which were in effect when the data was recorded. You will be prompted to hit any key, after which the Comscope will enter captured mode or start the selected application program.

5.5 Hardware Address
This menu identifies the hexadecimal base address of the printer port that the Comscope unit is connected to. The Comscope software will display the addresses of all printer ports identified by your PC's BIOS. You may select one of these or enter a different value at the "> " option.
The hardware address is stored in a file called CONFIG.OM3. This file also contains the default configuration that the Comscope will use when first started. To establish a new default configuration you must first select the desired options and then go to this menu. Hit the ENTER key to save the new configuration.

6.0 Submenu Function Keys
The mode submenus are entered by depressing ENTER when in the MODE menu of the main menu (Section 5.1). All four submenus have the same nine function keys defined.

6.1 F2 - Main Menu
Depressing function key F2 will return you to the main menu (Section 5.0.)

6.2 F3 - Review Captured Data
If no application routine has been selected, depressing function key F3 will put the Comscope in review mode (Section 13.0), allowing you to review captured data line activity. Captured data remains in memory until overwritten by new data.
Shift - F3 Depressing the Shift key and F3 simultaneously will deselect any application routine and enter review mode. Application programs must be deselected before reviewing captured data.

6.3 Shift F4 - Print Captured Data
Depressing the Shift key and function key F4 simultaneously will bring up the Print menu, which allows you to print a copy of data in the capture buffer. See Section 14.

6.4 F5 - Save Current Configuration
You may generate a named copy of the currently selected configuration for future use as described in Section 5.2 above. Depressing function key F5 will cause a box to appear in the center of the screen. Enter the name you want the configuration saved under. If you enter the name of a configuration that already exists the previous configuration will be overwritten. Do not use any extension (no '.') in the name. The Comscope will save the configuration in a file with the name you selected and the extension ". OM2."

6.5 F6 - Define A Search Sequence
The Comscope allows you to set up a sequence of events that it will search for. The sequence may be searched for in live data line activity or in captured data. The search facility may also be used by an application program. Depressing function key F6 will bring up the search menu where the sequence can be set up. See Section 11.

6.6 F7 - Toggle Control Lead Capture
When control lead capture is ON the Comscope will capture all control lead changes as well as displaying them. If control lead capture is OFF the Comscope will display the state of the leads but not capture them, so that control lead changes will not show in a journal file or when Reviewing Captured Data. The control leads are displayed at the lower left of the screen. Inverse video (black letters in a white box) indicates that the control lead is 'on,' while normal video indicates that the lead is 'off.' NOTE: There are situations where noise on unused control leads can consume excessive processor time and buffer space and control lead capture must be OFF. Depressing F7 will switch control lead capture ON and OFF as shown to the right of the F7 prompt at the lower middle of the screen.

6.7 F8 - Toggle Time Stamping
When time stamping is enabled, the Comscope will place time stamps in the capture buffer as often as possible. The time (to 1/100 seconds) will be displayed in the lower right corner of the data screen when in captured mode. Time stamping is given a lower priority than displaying data so that at higher data rates the time stamps may be rather infrequent or even non-existent. Time stamping can as much as quadruple the size of the real time buffer so you may wish to turn it off when journalling data. Depressing F8 will switch time stamping ON and OFF as displayed to the right of the F8 prompt at the lower right of the screen.

6.8 F9 - View Data Line Activity
If no application program has been selected (Section 5.3) depressing function key F9 will cause the Comscope to immediately enter live mode to display data line activity. See Section 12.
If an application program has been selected it will be started, with the application directly accessing the serial data line.
Shift - F9 Depressing the Shift key and F9 simultaneously deselect any application routines and cause the Comscope to enter live mode.

6.9 F10 - Exit Program
Depressing F10 will exit the Comscope program and return control to DOS.

7.0 Asynchronous Submenu

This screen is entered by depressing ENTER when ASYNCHRONOUS is selected in the MODE menu in the main menu (Section 5.1). This screen has six pull down menus; SPEED, BITS/CHAR, STOP BITS, PARITY, code, and JOURNAL, and eight function keys.

7.1 General Information
The Comscope samples data with a clock 16 times the bit rate. It expects one start bit and at least one stop bit time. Application programs can generated data with 1, 1.5, or 2 stop bits. Absence of a stop bit is called a framing error. The Comscope expects and generates data with the low order bit transmitted first. Characters with parity or framing errors are displayed in color.

7.2 Speed
This menu selects the bit rate of the data. You may select one of the listed rates or enter the decimal value of a different rate at the "> "option. The maximum rate is 115200. Allowable rates are defined by the formula bit rate = 230400/x where x is an integer (whole number) between 2 and 65535. If you enter a non-allowable rate, it will be mapped to the next higher allowable rate.

7.3 Bits/Char
This menu selects the number of data bits in each character, not including parity, start, or stop bits. If less than 7 bits/characters is selected the unused bits will be displayed as '0's.

7.4 Stop Bits
This menu selects the number of stop bits for data generated by an application program. Asynchronous data can be generated with 1, 1.5, or 2 stop bits. (The Comscope can receive any data with 1 or more stop bits.)

7.5 Parity
If selected, the Comscope will check each data character for either even or odd parity. Characters with bad parity are displayed in color. Application programs can generate data with the parity selected by this menu. The parity bit is the high order bit i.e. the last bit transmitted before the stop bit.
The Comscope includes two other options for handling 9 bit characters. In these protocols, the 9th bit is used to differentiate between data and command characters. The Comscope will display characters with the 9th bit set in color, and characters with the 9th bit equal to zero in normal video. The 'FLGl' option selects data with the 9th bit as the least significant bit (the bit transmitted first), and 'FLGm' selects data with the 9th bit transmitted last (just before the stop bit(s)). Note that the Comscope will not generate 9 bit data.

7.6 Code
The Comscope will display the names of all the code translation files (files with .OM5 extension) in the current directory. Select the name corresponding to the coding of the data you are monitoring. Note that you can switch between hexadecimal and the selected code while monitoring or scrolling through data (Sections 12.5 and 13.12.3.) Data generated by an application program will be translated to the selected code as listed in the tables in the PROGRAMMER'S MANUAL.

7.7 Journal
The Comscope allows you to save a copy of captured line data to a disk file for later analysis (see 5.4 above). Journal files are named xxxxx. OM1, where xxxxx is the name displayed in this menu. This menu displays the names of journal files already existing in the current directory. You may select one of them or enter a new name at the ">" option. Do not enter the ". OM1" extension. Note that if you select a file that already exists the previous data will be overwritten.

8.0 Synchronous Submenu

This screen is entered by depressing ENTER when SYNCHRONOUS is selected in the MODE menu (Section 5.1). This screen has eight pull down menus, code, PAD CHAR, BITS/CHAR, SYNC SEQUENCE, DATA, ORDER, SPEED, and JOURNAL, and eight function keys. The eight function keys functions are described in Section 6 above.

8.1 General Information
The Comscope supports character oriented synchronous protocols such as BiSync. These types of protocols assign special meaning to various characters or character sequences and uses these special characters to delimit data and manage the data link. The Comscope does not support character count protocols such as DEC's DDCMP. The Comscope can be set to search for any 6, 8, 12, or 16 bit synchronization sequence. It will display data received after this sequence until two consecutive PAD characters are not displayed. The Comscope does not check parity or CRC in this mode. The Comscope can support data with the least significant or most significant bit of each character transmitted first. It supports data with normal or inverted polarity.
The Comscope also has two special modes for IBM BiSync and IPARS data. The Comscope will verify the CRC of data frames in these modes. The special modes are selected via the BCC menu, as described below.
Data blocks generated by application programs in synchronous mode will begin with the selected synchronization sequence and end with a two character CRC-16 sequence and at least one pad character. Idle time between frames consists of pad characters. Application programs may also generate synchronous frames without the CRC characters. Note than an application program may override one or more of the options selected.

8.2 Code
The Comscope will display the names of all the code translation files (files with .OM5 extension) in the current directory. Select the name corresponding to the coding of the data you are monitoring. Note that you can switch between hexadecimal and the selected code while monitoring or scrolling through data (Sections 12.5 and 13.12.3). Data generated by an application program will be translated to the selected code as listed in the tables in the APPLICATION manual.

8.3 Parity
The Comscope will check for even or odd parity if selected. Characters with the wrong parity will be displayed in color. The parity bit is in addition to the bits/character selected in 8.6 below. For instance, 7 data bits with even parity is interpreted by the Comscope as 8 bits/character total.

8.4 BCC - Block Check Character
When CRC-16 is selected, the Comscope will interpret line data as IBM BiSync. The Comscope automatically recognizes both transparent and normal data. In this mode, the last character of a frame with CRC will be highlighted if the CRC is correct. If the CRC is not correct, the last character of the frame will be displayed in color. When CRC-6 is selected and Bits/Character is set to 6, the data will be interpreted as IPARS. The last character of frames with CRC will be displayed the same way as BiSync.

8.5 Pad Char
The Comscope interprets two successive pad characters as the end of a block. This menu displays the hexadecimal value of the pad character. You can enter the hexadecimal value of the pad character at the "> " prompt. Note that only the number of bits selected in Section 8.6 below will be significant. Idle time between data blocks generated by an application program will be continuous pad characters.

8.6 Bits
This menu selects the number of data bits in each character. If less than 8 bits per character are selected the unused upper bit(s) will be displayed 0s. Note that the number of bits per character selected also affects the synchronization sequence used, as described in Section 8.5 above.

8.7 Sync
This menu selects the sequence used to establish character synchronization. You may select either a one or a two character sequence. If the number of bits per character is 5 or 6 the synchronization sequence will be one or two bit characters, i.e. 6 or 12 bits long for 7 or 8 bits per character the synchronization sequence will be 8 or 16 bits long. Enter the hexadecimal value of either one or two characters (separated by a comma) at the "> " prompt. If the Comscope does not see a comma in the third position, it will search for a single character synchronization sequence.
Data blocks generated by an application routine will be preceded by the synchronization sequence selected in this menu.

8.8 Data
This menu selects whether the data has normal or inverted polarity. See the page for the electrical interface adapter you are using to identify what normal polarity is. This menu also selects the polarity of the data generated by an application routine.

8.9 Order
This menu selects whether data is transmitted with the least significant or most significant bit first.

8.10 Speed
This menu selects the bit rate of the clock that will be generated by the Comscope when emulating a DCE.

8.11 Journal
The Comscope allows you to save a copy of captured data to a disk file for later analysis. See Section 7.7 above.

9.0 HDLC Submenu
This screen is entered by depressing ENTER when HDLC is selected in the MODE menu (Section 5.1.) This screen has six pull down menus, IDLE, DATA CODING, BITS/CHAR, code, SPEED, and JOURNAL, and eight function keys. The functions of the eight function keys are described in Section 6 above.

9.1 General Information
High level Data Link Control (HDLC) is the frame level definition that is the basis for a number of modern protocols such as SDLC and X.25. There are only two special characters: flag and abort. A flag character is '01111110' and abort is any sequence of 7 or more consecutive '1's. Flag characters are used to delimit a frame of data. The two bytes immediately preceding the closing flag are the CRC error checking bytes. An abort terminates the frame being transmitted and indicates that it is not valid. Zeros are inserted in the data stream after five consecutive '1's so that will never appear as a flag or abort character. The Comscope will display the last character in a frame (normally the second CRC byte) in the opposite type of video from the rest of the frame. If the CRC check is not valid, the last character will be displayed in color. Data frames generated by an application program in HDLC mode will begin with a flag and end with the two byte CRC and a closing flag. Idle line fill is selectable between steady MARK (all '1's) and flags. Application programs can also generate frames with no CRC and frames ending with an abort.

9.2 Idle
This menu selects the idle line fill between frames generated by an application program. The Comscope can generate FLAG characters or constant MARK ('1's) between the data frames.

9.3 Data Coding
The Comscope can monitor or generate data transmitted as Non-Return-to-Zero (NRZ, the normal method) or Non-Return-to-Zero-Inverted (NRZI). NRZI data may be clocked using the external clocks (NRZIc) or the Comscope can derive the clock using a Phase Locked Loop (NRZId). If you select NRZId, you must select the nominal bit rate of the data in Section 9.6 below.

9.4 Bits/Char
This menu selects the number of bits in each character between the opening flag and the two CRC bytes (flag and CRC characters are always 8 bits). If less than eight bits per character is selected, the unused upper bit(s) will be displayed as 0s.

9.5 Code
The Comscope will display the names of all the code translation filed (files with .OM5 extension) in the current directory. Select the name corresponding to the coding of the data you are monitoring. Note that you can switch between hexadecimal and the selected code while monitoring or scrolling through data (Sections 12.5 and 13.12.3). Data generated by an application program will be translated to the selected code as listed in the tables in the APPLICATIONS manual.

9.6 Speed
This menu selects the nominal bit rate when monitoring or generating NRZId coded data (Section 9.3 above). For all other modes, this menu selects the bit rate of the clock that will be generated by the Comscope when used with a DCE type adapter.

9.7 Journal
The Comscope allows you to save a copy of captured data to a disk file for later analysis. See Section 7.7 above.

10.0 Unknown Submenu

This screen is entered by depressing ENTER with UNKNOWN selected in the MODE menu (Section 5.1). This screen has six menus, SPEED, BITS/CHAR, code, DATA, ORDER, JOURNAL, and eight function keys. The functions of the eight function keys are described in Section 6 above.

10.1 General Information
The UNKNOWN mode provides the maximum amount of information when the type of data transfer on a channel is unknown. The unknown mode merely shifts in the specified number of bits and displays them as one character. Either you can use the line clocks or set the Comscope to generate its own internal clock, which will sample the two data, leads at the specified bit rate. An application may also generate data in unknown mode.

10.2 Speed
Select the internal clock rate to be used or select EXT to use the line clock. If send or receive data is not displayed with EXT selected it indicates that the appropriate clock is not present. Selecting one of the other rates sets the Comscope to sample the data leads with its own internal clock, at the specified number of bits/second. You can also enter a rate not shown by entering the decimal value at the ">" prompt. The rate must be an integral multiple of the system clock as explained in Section 7.2 above.

10.3 Bits/Char
This menu selects the number of bits that will be assembled and displayed as one character. If less than 8 bits per character are selected, the unused upper bit(s) will be 0s.

10.4 Code
The Comscope will display the names of all the code translation files (files with .OM5 extension) in the current directory. Select the name corresponding to the coding of the data you are monitoring. Note that you can switch between hexadecimal and the selected code while monitoring or scrolling through data (Sections 12.5 and 13.12.3).
In this mode data codes are likely to produce garbage since there is no character synchronization. However, you may want to use one of these codes with the bit scroll keys in the scroll mode (Section 13.10) to help identify valid data. You can return to this menu and load a different code then redisplay the data in that code by hitting F3.

10.5 Data
This menu selects whether the data is normal or invented polarity. See the page for the electrical interface adapter you are using to identify what normal polarity is. You can change this option when scrolling through captured data to help identify whether data is normal or reverse polarity. Leave scroll mode (Section 13) with function key F2, select the opposite polarity at this menu, then re-enter scroll mode by hitting function key F3.

10.6 Order
This menu selects whether data is transmitted least significant or most significant bit first. You can change this option when scrolling through captured data to help identify whether the data was transmitted least or most significant bit first. Leave scroll mode (Section 13) with function key F3.

10.7 Journal
The Comscope allows you to save a copy of the data you are monitoring to a disk file for later analysis. See Section 7.7 above.

11.0 Search Menu

This screen is entered by depressing F6. This screen consists of four function keys and up to four menus. With this screen you do not select the menus with the left and right arrow keys; they are brought up as needed by the Comscope for additional information. You use the up and down arrow keys as usual to select a trap item from the left menu. Depressing the ENTER key will bring up a menu in the middle of the screen if more sub-options exist. The selected trap item will then appear in the 'menu' at the right, which is really only a list. You scroll through or change this list. You can only add to it or hit function key F6 to erase the list.

11.1 General Information
The search menu allows you to specify a sequence of events for which the Comscope can search. In live mode, you may either highlight data or stop capture when the sequence is found. If you select 'stop capture', the Comscope will stop capture and enter captured mode (Section 13) with the cursor positioned after the search sequence. When a search sequence is in effect there will be an 'S' on the second line from the bottom of the live mode display. The search menu may also be called from captured mode (Section 13.13). In this case the Comscope will search the capture buffer or the specified sequence and put the cursor immediately following the last element of the sequence. If the sequence is not found the cursor will be at the end of the buffer and the 'S' indicator will be on. Each sequence may consist of up to 16 'events' as described below.
Setting up a search sequence is generally an intuitive process, but you should be aware of exactly how the Comscope processes search consequences. The foreground part of the Comscope reads entries out of the capture buffer and displays them on the screen. As it is doing this it compares the entries to the search sequence. If an entry matches the first item in the search sequence the Comscope will then begin comparing with the second item in the sequence, and so on until the last item in the sequence has been found. Certain conditions will cause the Comscope to reset the sequence, that is, go back and start searching for the first event again;

• If the next item in the search sequence is a data character and a different data character is found in the buffer the sequence will be reset. Note that the Comscope differentiates between transmit and receive: If the Comscope is searching for a transmit data character it will not reset on a receive character.
  
  
• If the next item in the search sequence is a control lead turning "ON" or "OFF" and the opposite change is found the sequence will be reset. Note that you can only search for control leads changing, since this is the only time an entry is made in the buffer. In addition, control lead capture must be ON in order to search for control lead changes.
  
  
• If the next item in the search sequence is the beginning or end of a break or abort and the opposite (beginning instead of end or vice versa) is found the sequence will be reset.
  
  
• If the next item in the search sequence is the end of a good or a bad frame in HDLC mode and the opposite end of frame (bad instead of good or vice versa) is found the sequence will be reset.
  
  A search is 'set' when you leave this menu. Once the search sequence is found then the search is disabled but the search remains in memory. You can re-enable the search by calling the search menu and then exiting it (i.e. hit F6 then F2).
  
  11.2 Control Leads
  RTS, CTS, DTR, DSR, CD, and RI. Selecting one of these control leads will bring up an option menu requiring you to select ON or OFF or ANY CHANGE. Select whether you want the search condition to be the selected lead turning on or off or either.
  
  11.3 End of Frame
  End of frame is only defined in the HDLC mode. Selecting end of frame will bring up an option menu requiring you to select Transmit or Receive. Select whether you want the end of a transmit or a receive frame. The Comscope will then bring up another option menu requiring you to select Good CRC, Bad CRC, or Any Frame. Select a good frame, an errored frame or either one. An aborted frame must be selected via Section 11.4 below.
  
  11.4 Break/Abort
  Break is only defined in asynchronous mode and abort is only defined in HDLC mode. Selecting break/abort will bring up an option menu requiring you to select Transmit or Receive. Select whether you want a transmit or receive break or abort. The Comscope will then bring up another option menu requiring you to select START or END. You must select whether you want to trap at the beginning or end of the break or abort. The end of an abort in this case refers to the first 0 after an abort. This may also be useful on lines with idle mark.
  
  11.5 Parity Error
  Parity is only defined in asynchronous mode. Selecting parity error will bring up an option menu requiring you to select Transmit or Receive. Select whether you want to trap on a transmit or receive parity error.
  
  11.6 Framing Error
  Framing error is only defined in asynchronous mode. Selecting framing error will bring up an option menu requiring you to select Transmit or Receive. Select whether you want to trap on a transmit or receive framing error.
  
  11.7 Tx Data
  This option selects valid transmit data characters. The display line in the right hand menu will contain four elements when this selection is complete. The first is the mnemonic 'Tx DATA.' The second is the hexadecimal value of the character. The third, in single quotes, is the character representation, mainly for text, and the fourth is the hexadecimal value of the mask. The mask value is 'AND'ed with the received data before comparing with the character being searched for. This allows you to eliminate the parity bit or only look for certain bits within a character.
  Selecting Transmit data brings up an option menu requiring you to enter the value of the character on which to trap. The top option within this menu allows you to press the key corresponding to the character on which you want to trap. The code you are using must be set before you use this option. The mask value will be set according to the number of bits per character selected. If parity is selected the high order bit will be masked out.
  Selecting the second line of this menu allows you to enter the hexadecimal value of the character on which you want to trap. Entering a value will overlay the FF that is displayed on this line. The Comscope will bring up a second option menu which requires you to enter the hexadecimal value of the data mask.
  
  11.8 Rx Data
  This option selects valid received data characters. The format is the same as Section 11.7 above.
  
  11.9 Sync Sequence
  Synchronization is only defined for the synchronous mode (see Section 8.0). Selecting this option will bring up an option menu requiring you to select either transmit or receive. Select whether you want to trap on a transmit or receive synchronization sequence being detected.
  
  11.10 When Found….
  This option selects the action to take when the selected sequence is found. When you hit ENTER the Comscope will bring up an option menu with the following five options:
  
  11.10.1 Delay
  This option instructs the Comscope to delay the specified number of events before taking any further action. Selecting this option will bring up an option menu requiring you to enter the decimal value of the delay you wish. The delay can be in the range of 1 to 32000. An event can be any one listed in Section 11.1 above or a time stamp which can take up 1 to 4 event locations.
  11.10.2 Highlight On
  This option will cause all succeeding data to be highlighted. This option has no effect in captured mode. Other search events may follow 'Highlight On.' 'Highlight On' is often used with 'Highlight Off' and 'Search Again' below to highlight a string of data.
  11.10.3 Highlight Off
  This option will cause all succeeding data to be displayed normally.
  11.10.4 Stop Capture
  This option will cause the Comscope to stop data capture and jump to Review Captured Data mode (Section 13) when the search sequence is found. The Comscope defaults to 'Stop Capture' if 'Search Again' below is not specified at the end of a sequence.
  11.10.5 Search Again
  This option will cause the Comscope to reset the search sequence, i.e. to go back and begin searching for the first item in the search sequence again. This is normally used with 'Highlight On' and 'Highlight Off.'
  
  11.11 Trap Menu Function Keys
  11.11.1 F2 - Return From Search Menu Depressing function key F2 will return you to where you were when you called the search menu. If you called the search menu from Review Captured Data mode (Section 13) the Comscope will search the capture buffer for the selected sequence, positioning the cursor after the next occurrence of the sequence or the end of the buffer if not found. If you called the search menu from the other menus, the selected sequence will be enabled for when you begin Viewing Live Data (Section 12.)
  11.11.2 F6 - Clear Search Sequence
  Depressing function key F6 will erase whatever search sequence may have been selected. F6 is the only way to 'edit' a search sequence or to cancel one once selected.
  11.11.3 F10 - Exit Program
  Depressing the function key F10 will exit the Comscope program and return to DOS.
  
  12.0 View Data Line Activity
  
  12.1 General Information
  In live mode data is captured and displayed on the screen. The display is full duplex. There are really 7 rows (11 in EGA mode) of display data: A transmit data character on top and the corresponding receive character beneath it. If there is no corresponding transmit or receive character, the space will be blank. The states of the control leads are displayed on the bottom row. See Section 2 for the meaning of these leads. At the left of the row immediately above this is a reminder that function key F1 will bring up a brief help screen. To the right of this is the name of the transaction code file, which indicates the coding of the data, such as ASCII or IPARS. To the right of this are indications of whether journalling, a search sequence, or an application program is in effect. A 'J' indicates data is being journalled to a file, an 'S' indicated that a search sequence is in effect, and an 'A' indicates that an application is in control. If either of these conditions is not in effect there will be a dot in the appropriate location.
  If an application program is active there may be fewer lines of display data than described above or none at all. An application may or may not support the function keys described below. The documentation for the application will detail this.
  There are seven actions that can be taken in live mode, accessed via the function keys as described below.
  
  12.2 F1 - Help
  Depressing function key F1 will bring up a menu describing the functions of the seven function keys described here and the meanings of various elements of the live mode display. Note that data is accumulating in the capture buffer and cannot be displayed while you are viewing the help screen. If you spend too long in the help screen, the buffer may overflow, stopping data accumulation. The screen is thus intended only for a quick reminder.
  
  12.3 F2 - Return
  Depressing F2 will halt data capture and display and return you to the screen from which you entered live mode.
  
  12.4 F3 - Enter Scroll Mode
  Depressing F3 will cause the Comscope to stop data capture and display and enter captured mode (Section 13).
  
  12.5 F4 - Toggle Display Code
  Depressing F4 changes the display from the selected data code to hexadecimal or back again.
  
  12.6 F6 - Define A Search Sequence
  Depressing F6 will take you to the search menu (Section 11). Note that data is accumulating in the capture buffer and cannot be displayed until you return from the search menu. If you spend too long in the search menu, the buffer may overflow, stopping data accumulation. Calling the search menu from live mode is thus not recommended except in situations with little data activity.
  
  12.7 F10 - Exit Program
  As at all places in the Comscope program, depressing F10 terminates the program and returns to DOS.
  
  13.0 Review Captured Data
  
  13.1 General Information
  Captured mode allows a detailed analysis and viewing of data captured in live mode. It may be entered from live mode or when examining a journal file. The captured mode screen is very similar to the monitor mode screen with the following additions:
  At the bottom right hand of the screen, you will see four two-digit numbers. This is the time stamp in hours, minutes, seconds, and 1/100 seconds. If time stamping was not enabled (see Section 4.6) then the time will not change and will be the time when capture started.
  At the right of the second line from the bottom will be a brief explanation of the current entry in the capture buffer. The cursor is always immediately to the right of the current data. Entries in the buffer may be data or other events: To view the exact chronological order move the cursor to the left of the data in question, then use the right arrow key repeatedly and read the explanation line for each keystroke. You are actually stepping through the buffer one entry at a time.
  The arrow keys at the right of the keyboard enable you to move through the data. Note that in scrolling through the data the Comscope is designed so you never lose your place. The cursor can only be moved to data already displayed on the screen. If, for instance, you want to move a whole screen (or 'page') at a time your first keystroke moves the cursor to the upper left hand corner and the next keystroke moves that data to the lower right hand corner. While this may slow your rate of movement through the buffer somewhat, it makes it much easier to keep track of the relationship of various data.
  
  13.2 Home
  The home key will display the first page of data in the buffer. If the buffer is full, it may take several moments for the Comscope to get back to the beginning of the buffer.
  
  13.3 End
  The end key will display the last page of data in the buffer. If the buffer is full, it may take several moments for the Comscope to get to the end of the buffer.
  
  13.4 Pgup
  The page up key moves the cursor back one screen at a time. If the cursor is in the upper left hand corner, the data will be scrolled down one row, if not, the cursor will be moved to the lower left hand corner.
  
  13.5 Pgdn
  The page down key moves the cursor ahead one screen at a time. If the cursor is in the lower right hand corner, the data will be scrolled to the upper left corner, if not, the cursor will be moved to the lower right corner.
  
  13.6 Up Arrow
  The up arrow moves the cursor back one row at a time. If the cursor is at the top row, the screen will be scrolled down one row, if not, the cursor will be moved up one row.
  
  13.7 Down Arrow
  The down arrow key moves the cursor ahead one row. If the cursor is in the bottom row, the screen will be scrolled up one row, if not, the cursor will be moved down one row.
  
  13.8 Left Arrow
  The left arrow key moves back one entry in the buffer. It does not necessarily move the cursor. The new entry will be identified on the second line from the bottom and the time or control lead indications will be updated if appropriate.
  
  13.9 Right Arrow
  The right arrow key moves ahead one entry in the buffer. It does not necessarily move the cursor. The new entry will be identified on the second line from the bottom and the time or control lead indications will be updated if appropriate.
  
  13.10 Shift-Left Arrow
  Pressing the shift key and the left arrow key when viewing data captured in the UNKNOWN mode shifts the character boundary by one bit. The low order bit of the previous character (the one to the left) becomes the high order bit. Since there is no character synchronization in UNKNOWN mode, the character boundaries are arbitrary. This key may be useful in identifying the format of unknown protocols. Bit shifting the data until clear text or some recognized pattern is seen often helps identify the data.
  
  13.11 Shift-Right Arrow
  Pressing the shift key and the right arrow key when viewing data captured in the UNKNOWN mode shifts the character boundary by one bit. The high order bit of each character becomes the low order bit of the previous character (the one to the left.) See Section 13.10 above (shift left).
  
  13.12 Captured Mode Function Keys
  There are four function keys that can be used in the captured data mode.
  13.12.1 F1 - Help
  Depressing F1 will bring up a help screen describing the function keys and scroll keys that can be used in capture mode.
  13.12.2 F2 - Return
  Depressing F2 will return you to where you were when you entered captured data mode.
  13.12.3 F4 - Toggle Display Code
  Depressing F4 will change the display form the selected data code to hexadecimal or back again.
  13.12.4 Shift F4 - Print Captured Data
  Holding down the shift key and hitting function key F4 will bring up a print menu, which will allow you to print a copy of data in the capture buffer. See Section 14.
  
  13.13 F6 - Define A Search Sequence
  Depressing F6 will bring up the search menu (Section 11) which will allow you to enter a sequence to search for in the capture buffer. After hitting function key F2 in the search menu the Comscope will begin searching from the current cursor position until the desired sequence or the end of the buffer is reached. The Comscope will display a screen of data with the end of the sequence at the lower right hand corner of the screen. If the sequence is not found the 'S' indicator will be on, otherwise it will be a dot.
  Note that the Comscope searches from the current cursor position. Scroll mode is entered with the cursor at the end of the data buffer, so you must get to the beginning of the buffer, or before the area to be searched, usually with the Home key.
  
  13.14 F10 - Exit Program
  As at every point in the Comscope program, depressing F10 will terminate the Comscope program and return to DOS.
  
  14.0 The Print Menu
  
  The print facility enables you to get a printed copy of data in the capture buffer. The print menu is entered by holding down the shift key and hitting F4. The print menu enables you to set the number of characters in each line, the number of lines in each page, what the Comscope will send at the end of each line, and at what points in the capture buffer to start and end printing. The default line length, page length, and end of line sequence are stored in the config.om3 file. The Comscope sends the output to the DOS standard print file (PRN:).
  
  14.1 Line Length
  This menu selects the number of characters in each line. You may select the standard 80 or 132 character options or enter a different number of characters at the "> " prompt. The length must be between 5 and 132 characters.
  
  14.2 Lines/Page
  This menu selects the number of lines per page. You may select the standard 55 line option or enter a different number at the "> " prompt. The Comscope generates a form-feed character after the specified number of line.
  
  14.3 End of Line
  The Comscope can send either a carriage return or a line feed character at the end of each line.
  
  14.4 Begin
  This menu selects the point in the capture buffer where printing will begin. You can select the BEGINning of the capture buffer or enter the buffer address of the point where you want printing to start at the "> " prompt. The buffer address of where the cursor was when you hit F5 is displayed near the lower right hand corner of the screen as "Current buffer pointer: xxxxx". This value is copied to the ">" option if that option has not been selected yet. While in scroll mode you can move the cursor point to where you want printing to start, hit F5 and select the ">" option. You may then hit F2 to return to scroll mode and move the cursor to the point where you want printing to stop and go to the END menu as described below.
  
  14.5 End
  This menu selects the point in the capture buffer where printing will stop. You can select the END of the capture buffer (or the end of the file if you are EXAMINEing a FILE (Section 5.4)) or enter the buffer address of the point where you want printing to stop at the ">" prompt. The buffer address of where the cursor was when you hit F5 is displayed near the lower right corner of the screen as "Current buffer pointer: xxxxx". This value is also copied to the ">" option if that option has not been selected yet. You may use the cursor keys in scroll mode to find the end point in the capture buffer before hitting F5.
  
  14.6 Print Menu Function Keys
  14.6.1 F2 - Return from Print Menu
  This function key will return you to the scroll mode display. The options you have selected will remain in effect.
  14.6.2 F4 - Toggle Display Code
  The Comscope can print the data in the selected display code or in hexadecimal. F4 will toggle from the selected display code to hexadecimal and back again.
  14.6.3 F9 - Start Printing
  The Comscope will begin printing when you hit F9. A window will open in the center of the screen that displays the buffer address being printed. Note that most printers have buffering so the displayed address will likely be ahead of what is actually being printed.
  14.6.4 F10 - Exit Program
  F10 Returns you to DOS.
  
  14.7 Print Format
  The Comscope uses a four line format to display data. The top two lines are data generated by the DTE, referred to as transmit (Tx) data in scroll mode. The second two lines are data generated by the DCE or receive (Rx) data. Data that are represented by a two letter mnemonic, such as the synchronization character represented by 'S' over 'Y' will use both lines of the DTE or DCE pair with the first character directly over the second character. In hexadecimal print all characters are represented by two characters.
  Control lead changes are printed using all four lines. The bottom character will be a '+' if the signal went active, or '-' if it went inactive. 'RTS' will be 'R' over 'T' over 'S' over '+' or '-'. 'CD' is printed as 'DCD' and 'RI' is printed as 'RIN'.
  The detection of synchronization is printed 'S' over '!'. A 'space' character is printed as "over". Break of abort is printed as '!' over '!'.
  
  15.0 BERT
  
  The BERT (Bit Error Rate Test) program option enables you to obtain a statistical measure of the quality of a data line. The BERT option records the number of bits, characters, or blocks with errors. The program may be used in a loop-back mode, with another PC Comscope or BERT tester, or derive error rates from live data.
  The BERT program consists of three distinct tests:
  The BER (Bit Error Rate) test generates and checks a continuous stream of bits and measures the number of bits in error. The test can generate and synchronize with a number of standard bit patterns, including those generated by other manufacturers' equipment. This test also derives a block error rate figure and the error percentages specified in G.821. The BER test conforms to CCITT recommendations V.52 and G.821. However, the BER test does not attempt to normalize the figures to 64 KBPS as specified in Annex D of G.821 - all figures assume the actual bit rate is 64 KBPS.
  The BLER (Block Error Rate) test derives a block error rate figure from live HDLC protocol data. The BLER test reports the number of aborted, short, and long frames and frames with CRC errors. The BLER test also monitors for Reject and Selective Reject frame.
  The CHER (Character Error Rate) test generates and checks asynchronous data. The test can generate and synchronize with the same standard bit patterns as the BER test, although they will of course include start and stop bits for each character. The test can also synchronize on an arbitrary data stream and report the number of breaks, parity, and framing errors, allowing you to derive performance figures from live asynchronous data lines.
  
  15.1 Running The BERT Program
  The BERT option is run by selecting 'BERT' from the PROGRAM OPTION menu as described in the PC Comscope User's Manual. Highlight 'BERT' and then hit the function key F9. The BERT program will force the PC Comscope to Capture (live) mode when started, so the BERT will not work with captured or disk journalled data. You generally do not need to select a data mode before starting BERT since the test will configure the PC Comscope as needed.
  However:
  
  
• The BERT will select its default mode (Section 15.3 below) based on the data mode: If started in Asynchronous mode the BERT will default to CHER mode. All other modes will cause the BERT to default to BER mode.
  
  
• The SPEED option, for DCE adapters or CHER mode, will default to the speed selected when the BERT is started.
  
  
• When using the FOX pattern in CHER mode, the bits/characters, parity, and stop bits MUST be selected before starting the BERT test.
  
  15.2 Configurations
  Error rate testing may be done in one of three configurations: loopback, end-to-end, or live data monitoring.
  In a loopback configuration, the transmitted data is 'looped back' at the remote end of a circuit, so that the BERT test receives the same data it transmitted.
  In end-to-end testing an error rate tester is placed at each end of the circuit. Each device tests the data transmitted by the other. The BERT test can synchronize on data transmitted by another PC Comscope or another manufacturer that transmits the standard patterns described in Section 15.5 below. End-to-end testing has the advantage of identifying which direction data errors occur in.
  Live data monitoring is a unique feature of the PC Comscope BERT test. The BERT test can synchronize on asynchronous or HDLC protocol data and record the number of errors that occur. This mode will typically be used with a passive MONITOR electrical adaptor to tap into a live data line. You select DCE or DTE (Section 15.4 below) to identify which data leg you want to look at. To test live asynchronous data select the bits/character and parity of the data before selecting the BERT test. Then select the FOX pattern of Section 15.5 below. To test live HDLC data select the BLER mode (Section 15.11).
  The BERT menus are accessed in the same way as other PC Comscope menus. You use the left or right arrow keys to highlight one of the options within that menu. See section 3.1 of the Programming Applications Manual (part # 0315-0108) if you need detailed information on using the menus.
  
  15.3 Mode
  The BERT program contains three distinct tests: Bit Error Rate (BER), CHaracter Error Rate (CHER), or BLock Error Rate (BLER). These three modes are described more completely in Sections 15.9 through 15.14.
  
  15.4 Interface
  You must tell the BERT program which electrical interface you are using. If you are using a DCE adapter the PC Comscope will be generating data on the Receive Data pin and will test the data coming in on the Transmit Data pin. If you are using a DTE adaptor the PC Comscope will be generating Transmit Data and testing Receive Data. If you are using a MONITOR adaptor on a live data line, you will select DCE or DTE to identify which data stream you want to test. To test Receive Data select DTE. To test Transmit Data select DCE.
  
  15.5 Pattern
  Select the data pattern to be generated by the PC Comscope. This is also the pattern that the BERT test will expect to receive if you are doing end-to-end testing.
  
  'MARK' is a continuous 1's pattern.
  
  'SPACE' is a continuous 0's pattern.
  
  '1:1' is an alternating 0's and 1's pattern.
  
  '1:3' is a pattern of a 1 followed by three 0's.
  
  '3:1' is a pattern of a 0 followed by three 1's.
  
  '1:7' is a pattern of a 1 followed by seven 0's.
  
  '7:1' is a pattern of a 0 followed by seven 1's.
  
  'CCITT-511' is the 511 bit pseudo random pattern of recommendation V.52.
  
  '1023' is a bit pseudo random sequence.
  
  'FOX' is the standard 'Quick Brown Fox' message.
  
  The FOX pattern is only defined in the CHER (asynchronous) mode. The FOX pattern is handled differently by the BERT test. The BERT test will send the standard 'Quick Brown Fox' message but only checks for breaks, parity, or framing errors on received data without verifying the actual data contents. This allows you to test live data lines with a MONITOR adaptor.
  
  15.6 Block Size
  This menu allows you to select or enter the number of 8 bit characters in each block. In the BLER mode received frames that are longer than this will be considered 'long' and in error. In BER mode, the block size will affect the Block Error Rate figure. Internally, the BERT reads in line data in blocks of the size selected. Each block with one or more bit errors is counted as a bad block. The block size also has a small effect on resynchronization's. If the BERT test finds 5 characters in a row with one or more bit errors its considers itself out of sync. It will discard the rest of the data in the block and resynchronize with the next block of data. You will also note that the block size is the minimum resolution of the counters. Making the block size small will slightly degrade the maximum speed the BERT test can run at.
  
  15.7 Speed
  This menu allows you to select or enter the bit rate of the data. It is only relevant in CHER (asynchronous) mode or with a DCE adaptor where the PC Comscope provides the data clocking. The speed will default to the speed in effect when the BERT test was selected, so you enter the speed either here or in the main PC Comscope program.
  
  15.8 BERT Function Keys
  15.8.1 F2 - Return to PC Comscope menus
  15.8.2 F10 - Exit from tests
  These two function keys actually have identical effect - they return you to the PC Comscope main program. 15.8.3 F6 - Toggle Data Display: ON/OFF
  You can have the line data displayed in the upper half of the screen or leave it off. Displaying the data will limit the maximum line speed you can run at but may be helpful when trying to get your configuration right. Hitting function key F6 will toggle the data display ON or OFF as indicated on this line. You can only turn data display on or off before starting the tests.
  15.8.4 F9 - Start testing
  
  15.9 The BER Test
  The BER test generates and analyzes a continuous stream of synchronous data bits. The patterns supported are such that the test can synchronize with any point in the stream. The BER uses the first 8-10 bits of the data stream to synchronize and then verifies all further data bits. If the test receives 5 consecutive 8-bit characters containing bit errors the test will consider itself out of sync and resynchronize.
  
  The BER test also reports a Block Error Rate figure. The blocks are somewhat arbitrary since the BER test does not actually generate data in blocks but a continuous stream. However, since many protocols generate data in blocks, so that any one bit error requires the whole blocks to be scrapped, this figure may give a more useful measure of line quality. You should select a block size near the average block size of the protocol to get the most meaning from this figure.
  
  Elapsed Time: hh: mm: ss
  This is the hours, minutes, and seconds since the test began or the test was last restarted with F6.
  
  Pattern
  This is the pattern selected in Section 15.5 above.
  
  Bits Received
  This value does not include the characters remaining in a block when an out-of-sync condition was detected.
  
  Sent
  This is the number of characters transmitted by the test. This figure is not exact. It is calculated from the elapsed time multiplied by the bit rate. If there are large differences between this value and the Bits Received it suggests either long out-of-sync times due to gross data errors or loss of data clocking, probably due to loss of carrier on the modem.
  
  Errored Bits
  This is the number of bits found to be in error. Note that this value does not include errored bits during an out-of-sync condition. Thus, you must check both the calculated error rate AND the number of resyncs to evaluate the condition of a line.
  
  BER
  This value is the number of bits in error divided by the number of bits received. The value is given in exponential notation, where 1.00E-006 is equivalent to 1 times 10 to the minus 6th.
  
  Blks Received
  This is the number of blocks received. The number of bits in each block is displayed in BITS/BLK below. The number of characters in each block (which is 1/8 the number of bits in each block) is selected in Section 15.6 above. The BER test reads and processes line data in blocks of the size selected.
  
  Sent
  This is the number of blocks transmitted by the BER test. Like 'SENT' above, this value is calculated from the elapsed time. The BER test does not actually generate data in blocks but in a continuous stream, so this figure is simply the number of bits transmitted divided by the block size.
  
  Errored Blks
  This is the number of blocks with one or more bit errors. Blocks during which an out-of-sync condition was detected are included in this figure.
  
  BLER
  It is the number of errored blocks divided by the number of blocks received. The value is given in exponential notation, where 1.00E-006 is equivalent to 1 times 10 to the minus 6th.
  
  Errored Seconds
  This is the percentage of seconds that had one or more bit errors. Seconds when the circuit was deemed 'unavailable' (see below) are not included in this calculation.
  
  Severely
  This is the percentage of seconds with bit error rates of 1/1000 or higher. Seconds during which an out-of-sync condition was detected are also considered severely errored. Seconds when the circuit was deemed 'unavailable' (see below) are not included in this calculation.
  
  Degraded
  This is the percentage of minutes with bit error rates of 1/1,000,000 or higher. Seconds when the circuit was deemed 'unavailable' (see below) are not included in this calculation.
  
  Unavail: or Unavail!
  This is the number of seconds the circuit is deemed 'unavailable.' The circuit is considered unavailable when the bit error rate is 1/1000 or higher for 10 consecutive seconds. The circuit is considered available again at the beginning of 10 consecutive seconds with bit error rates lower than 1/1000. When the circuit is unavailable, this line will read 'Unavail:'
  
  Sync: 'Out!' or 'In'
  This will display whether the BER test is currently 'In' sync with the data stream or 'Out!' of sync.
  
  ReSyncs
  This is the number of times the BER test has gone out of sync with the data stream. As explained above, the BER will attempt to resynchronize when it receives 5 consecutive 8 bit characters with bit errors.
  
  Bits/Blk
  This is the number of bits in each block received by the BER test. It is 8 times the block size selected in Section 15.6 above.
  
  15.10 BER Function Keys
  15.10.1 F2 - Freeze/Resume Display
  F2 allows you to temporarily halt updating of the display, to allow you to check or record the results to date. When you hit F2 to freeze the display this line will change to 'Resume display.' Hitting in F2 again will cause the numbers to be updated again. The test continues normally even when the display is frozen.
  15.10.2 F4 - Display Code
  If you have data display enabled (Section 15.8.3 above), F4 will change the display to HEXadecimal. Hitting F4 again will change it back to the selected display code.
  15.10.3 F5 - Inject Error
  Hitting F5 will invert the state of one bit in the stream generated by the PC Comscope, emulating the effect of a single bit error.
  15.10.4 F6 - Restart Test
  F6 resets the bits and blocks in error counters.
  15.10.5 F7 - Clear Errors
  F7 only resets the bits and blocks in error counters.
  15.10.6 F10 - Exit Test
  F10 stops testing and returns you to the BERT menus.
  
  15.11 The BLER Test
  The BLER testis used to derive the block error rate from live HDLC protocol streams. The BLER test will work with most protocols that use the HDLC format, including X.25 and SDLC. The BLER test will not work in loop-back or end-to-end configurations since it does not generate any data. The BLER test will thus be used only with MONITOR electrical adapters. The BLER test monitors for good, aborted, and long frames, and frames with CRC errors. It also monitors for Reject or Selective Reject frames that indicate an error took place in the opposite direction. The BLER test monitors both send and receive data streams but calculates the BLER for each differently. One of the data streams is assumed to be coming from data equipment adjacent to the PC Comscope and will thus not contain any errors. The BLER for this data is figured as the ratio of Rejects counted on the other data stream to the total number of blocks sent. The BLER test assumes that the remote end of the circuit will issue one Reject for each frame that is corrupted in transit. This is not necessarily true, so the actual BLER may be somewhat higher than what this test reports. The other data stream is assumed to be from a remote location and may thus contain errors. The BLER for this data stream is figured as the ratio of the sum of aborted, long, and frames with CRC errors to the total number of frames received. If you select DTE (Section 15.4 above), receive data will be assumed to be from the remote and transmit data will be assumed to be generated locally. If you select DCE, transmit data is from the remote and receive data is local. Typical setups will use the DTE setting. Following are the items reported by the BLER test:
  
  Elapsed
  This is the amount of time since the test started, or was restarted with F6 (Section 5.12.3 below).
  
  Block Size
  This block size was selected in Section 15.6 above. If you see very many 'long' blocks listed (RxLong below), you may have this value too small.
  
  RxGood
  This is the number of valid received data frames counted.
  
  RxCRC
  This is the number of receive data frames with CRC errors.
  
  RxAbort
  This is the number of aborted receive data frames.
  
  RxLong
  This is the number of receive data frames that contained more than the selected block size characters. Long frames may occur because the protocol actually sent a frame that was long or the closing flag of a frame may get a bit error and two consecutive frames appear to be concatenated. The BLER test does not distinguish between long frames with or without valid CRC.
  
  RxRej
  This is the number of receive data rejects counted. Note that the protocol will send a receive data reject because it detected an out-of-sequence condition on the transmit data side (normally due to a bit error).
  
  RxBLER
  If DCE (Section 15.4) was selected this figure will be the ratio of TxREJ to total receive data frames. If DTE was selected this figure will be the ratio of the sum of aborted, long, and receive data frames with CRC errors to the total number of receive data frames. The value is given in exponential notation, where 1.00E-006 is equivalent to 1 times 10 to the minus 6th, or 1/1,000,000.
  
  TxGood
  This is the number of valid transmit data frames counted.
  
  TxCRC
  This is the number of transmit data frames with CRC errors.
  
  TxAbort
  This is the number of aborted transmit data frames.
  
  TxLong
  This is the number of transmit data frames that contained more than the selected block size characters. Long frames may occur because the protocol actually sent a frame that was long or the closing flag of a frame may get a bit error and two consecutive frames appear to be concatenated. The BLER test does not distinguish between long frames with or without valid CRC.
  
  TxRej
  This is the number of transmit data Rejects counted. Note that the protocol will send a transmit data Reject because it has detected an out-of-sequence condition on the receive data side (normally due to a bit error).
  
  TxBLER
  If DCE (Section 15.4) was selected this figure will be the ratio of RxREJ to total transmit data frames. If DTE was selected this figure will be the ratio of the sum of aborted, long, and transmit data frames with CRC errors to the total number of transmit data frames. The value is given in exponential notation, where 1.0E-006 is equivalent to 1 times 10 to the minus 6th.
  
  15.12 BLER Function Keys
  15.12.1 F2 - Freeze/Resume Display
  F2 allows you to temporarily halt updating of the display, to allow you to check or record the results to date. When you hit F2 to freeze the display this line will change to 'Resume display.' Hitting F2 again will cause the numbers to be updated again. The test continues normally even when the display is frozen.
  15.12.2 F4 - Display Code
  If you have data display enabled (Section 15.8.3 above), F4 will change the display to HEXadecimal. Hitting F4 again will change is back to the selected display code.
  15.12.3 F6 - Restart Test
  F6 resets all counters to zero. It is the equivalent of exiting and then restarting the test. 15.12.4 F7 - Clear Errors
  F7 only resets the FxCRC, RxAbort, RxLong, RxREJ, TxCRC, TxAbort, TxLong, and TxREJ counters.
  
  15.13 The CHER Test
  The Character Error Rate test generates and checks asynchronous data characters and reports the ratio of characters with errors to total characters received. The CHER test can run in loop-back, end-to-end, or live data configurations. The CHER test supports the same data patterns as the BER test as well as the standard "Quick Brown Fox" message. The CHER test does not verify the data characters in the FOX pattern, but only counts the number of breaks, parity, and framing errors. This allows you to derive a CHER rate from live data streams. If you are using the FOX message, you must select the number of bits/character and the parity before starting the BERT program. For all other patterns the CHER test will force the PC Comscope to 8 bits/character, 1 stop bit, and no parity. The following are the items reported by the CHER test:
  
  Elapsed Time
  The time since the test was started or restarted with function key F6 (Section 15.14.4 below.)
  
  Pattern
  Displays the currently selected pattern being generated and checked for. If FOX is selected the test does not verify the content of received data characters.
  
  Chars Received
  This is the total number of characters received, including errored characters. Breaks are not included in this figure.
  
  Sent
  This is the number of characters transmitted by the PC Comscope.
  
  Good Chars
  The number of characters with no errors.
  
  Breaks
  The number of breaks received. A break is a space (zero) condition for 10 or more bit times. Breaks are not counted as errored characters and are not figured into the BLER calculation.
  
  Framing Errors
  The number of framing errors detected. A framing error means that the character did not include a valid stop bit.
  
  Parity
  The number of parity errors detected. This error will only show up when using the FOX pattern and parity enabled.
  
  Bad Data
  The number of characters with incorrect data. This error will not show up with the FOX pattern.
  
  CHER
  This is the ratio of the sum of characters with parity or framing errors or bad data to the total number of characters. The value is given in exponential notation, where 1.00E-006 is equivalent to 1 times 10 to the minus 6th.
  
  15.14 CHER FUNCTION KEYS
  15.14.1 F2 - Freeze/Resume Display
  F2 allows you to temporarily halt updating of the display, to allow you to check or record the results to date. When you hit F2 freeze the display this line will change to 'Resume display.' Hitting F2 again will cause the numbers to be updated again. The test continues normally even when the display is frozen.
  15.14.2 F4 - Display Code
  If you have data display enabled (Section 15.8.3 above) F4 will change the display to HEXadecimal. Hitting F4 again will change it back to the selected display code.
  15.14.3 F5 - Inject Error
  Hitting F5 will alter the data in a single character that it generates, producing a single 'Bad data' error.
  15.14.4 F6 - Restart Test
  F6 resets all counters to zero. It is the equivalent of exiting and then restarting the test.
  15.14.5 F7 - Clear Errors
  F7 only resets the breaks, parity, and framing error counters.
  15.14.6 F10 - Exit Test
  F10 stops testing and returns you to the BERT menus.
  
  16.0 Emulate Mode
  
  The EMULATE program option is selected by highlighting 'EMULATE' in the 'PROGRAM OPTION' menu on the opening screen of the Comscope.
  The EMULATE program option enables the Comscope to emulate one end of a data circuit, either Data-Terminal-Equipment or Data-Communication-Equipment (DTE or DCE.) An emulation program is entered using a state machine concept that enables rapid development of simple to complex emulation's. Programs may be saved to disk. Data generated or received during an EMULATE test is automatically captured to memory and may be journalled to disk for later analysis. The EMULATE option includes two test analysis options, a graph of timing or counted events, and a list of counter and timer values.
  
  16.1 The STATE Concept
  Test programs used during Emulate Mode operation are based on the State Diagram concept. A state diagram is a sort of flowchart of a procedure. A procedure is always in a particular 'state.' In each state, the procedure is waiting for one or more conditions or events to occur and will take certain actions when the condition occurs. The procedure will then move to another (or possibly the same) state, depending on which action occurred. A state diagram of a typical data communications procedure is shown below.
  In the Comscope, each State consists of one or more 'steps,' each of which is entered on one line in the edit steps dialog. Each state may consist of one or more conditions or events to wait for, and one or more actions to take for whichever condition is met first. Each condition may also include a State number to be executed next after the action(s) are taken. The 'next state' can be the same state the program is currently in. Each 'step' includes a State number, a wait-for condition, an action, and optionally, 'next state field.' Two wait-for conditions are unique: the 'default,' and 'continuation' conditions. A default wait-for condition tells the program to execute this step's action immediately upon entering the state. A continuation wait-for condition tells the program to execute this step's action when the wait-for condition in the line above it has been met. Note that the step above a continuation line must not have a next-state field entered.
  If no next-state field is entered for a step (or entered as zero), it means that the step's action will be taken, but the program will remain in the same state. This is not the same as having a next-state field of the current state, since the latter will cause any default steps to be re-executed and any time-out condition to be reset.
  You may prefer to think of states like a BASIC programming language, where each state is an IF-THEN-ELSE statement with GOTOs:
  
  1 IF '1 = 1' THEN (default wait-for)
  RTS = 1 : GOTO 2
  END IF
  
  2 IF 'CTS = 1' THEN
  SEND MESSAGE: GOTO 3
  ELSE IF TIMEOUT
  GOTO 10; (go print error message)
  END IF
  
  3 IF 'RECEIVED MESSAGE'
  Etc.
  
  16.2 Counter / Times
  EMULATE has 100 Registers numbered 0-99. The register is initialized with a value of zero. Whether a register functions as a counter or timer depends on how it is referenced by your program. The values in these counter/timers may be examined after the program is completed, and/or tallied to a histogram display.
  
  16.3 Histogram Display
  The histogram display allows you to make a statistical analysis of line data. The histogram is typically used for timing analysis but may be used for counts of any type. The X-axis (horizontal) is divided into 50 'bins,' each of which represents a value or range of values. The Y-axis (vertical) displays the number of times the tested variable is sampled (via the 'Tally' or 'S.T.C' actions,) EMULATE calculates which bin the variable value is in and increments that bin by one.
  You set up the range of values that each bin represents by the 'Histogram Bounds' menu (see SETUP below) which allows you to set the Lower and Upper bounds of the display. If, for instance, you set a lower bound of 0 and an upper bound of 100, each bin will have a range of 2. Bin 1 will represent values 0 & 1, bin 2 will represent values 2 & 3, and so on up to Bin 50 which will represent values 99 & 100. If a samples variable were 3 when a Tally instruction is executed, for instance, bin 2 would be incremented to 1.
  Here is a sample test program that you can use to generate a histogram. The program will record the number of 1/100 seconds between keystrokes as you type. If you don't hit a key for 3 seconds the program will stop and return to the EMULATE menus. The Histogram will then display a statistical graph of your typing speed.
  
  

  State	Wait for:	Action:	Next	State
  1	Default Up	Timer	1	2
  2	Key Hit	S.T.C.	1	1
  2	Timeout 300	End Test

  
  Tallied values below the lower bound or above the upper bound will be included in the first and last bin, respectively.
  
  16.4 EMULATE Mode Menus
  You start the EMULATE option by selecting 'EMULATE' from the 'PROGRAM OPTION' menu of the Comscope. EMULATE will then display a row of keywords on the top line of your display.
  Use the left and right arrow keys to select the top level menu item, type the highlighted letter, or click on the menu item with the mouse. If you use the keyboard, hit ENTER to drop down the menu. Use the up and down arrows to select the menu item, or type the highlighted letter, or click on the menu item with the mouse. If you use the keyboard, hit ENTER to execute the menu item. Notice that the bottom line of the display will have a brief description of each menu item as you highlight it.
  
  FILES
  This menu drops down three options: Load, Save, and New
  Select 'Load' to read in an EMULATE program that was previously saved. EMULATE will display a scrollable list of program files (program files must have a '.om7' extension.) Use the arrow keys to highlight the desired file and hit ENTER to load it.
  Select 'Save' to save a program you have entered to disk. EMULATE will bring up a dialog box. Enter a program name with extension '.om7' on the blank line or use the up and down arrow keys to select a displayed file name. Then hit Control-ENTER or click on the OK button with the mouse.
  Select 'New' when you want to erase a program in memory and start fresh.
  
  EDIT
  This Edit menu lets you enter or change an Emulate program. A program consists of two parts, steps and messages, although some programs may not include any messages. Steps and messages are entered via two different dialogs and either can be entered first. See Section 16.5 for details on entering steps and Section 16.6 for details on entering messages.
  
  SETUP
  This menu drops down two options: DCE/DTE and Histogram bounds.
  The DCE/DTE line switches between 'DCE' and 'DTE' each time you hit ENTER.
  Selecting 'Histogram Bounds' will bring up a small dialog that enables you to enter the lower and Upper bounds of the Histogram graph. EMULATE will automatically round whatever upper bound you enter to the next highest integral multiple of 50. The Histogram bounds must be set before collecting data, that is, before running the program.
  Both the DCE/DTE selection and the Histogram bounds are saved with a 'Save Program' command (see FILES above) and reloaded when the 'Load Program' command is used.
  
  EXECUTE
  Selecting this menu will bring up three option: Run Program, Show Histogram, and Show Registers.
  Run Program executes the program you have entered.
  Show Histogram displays the graphical histogram results of the data collected when you last ran your program. Note that the program must have 'Tally' (or S.T.C.) steps in order to have any histogram data to display.
  Show Registers brings up a list of all counter/timers that were used the last time you ran your program and their values when the program was stopped.
  
  QUIT
  This menu will bring you back to the Comscope menus. Whichever program is in memory, as well as the DCE/DTE setting and the Histogram bounds, will be saved to a file called 'EMULATE.OM3' which will be automatically reloaded the next time you start EMULATE.
  
  16.5 EDIT STEPS
  You edit steps by selecting 'Edit Steps' from the Edit menu. Selecting this option will bring up a dialog allowing you to enter, edit, or delete the steps that make up an Emulate program. Each step occupies one line on the display. The display is scrollable using the scroll keys, allowing up to 99 steps in a program. Use the TAB and Shift-TAB keys to move between fields in a step. To delete a step use the arrow keys to highlight the step. With a mouse, simply click on the Delete button. With the keyboard, hit F10 to highlight the 'Insert' button, then hit right arrow to highlight 'Delete,' then hit ENTER. Then hit ENTER again to the warning box, then hit TAB to get back to the edit box. To insert a blank step before the selected step click on the 'Insert' button, or use the same procedure as above for the keyboard, only don't use the arrow key to move off of the 'Insert' button. When you are done editing you can click on the 'Done' button or hit the ESCape key.
  
  STATE
  Enter a number between 1 and 99. Each step must have a state number and states must be entered in ascending order.
  
  WAIT FOR
  When you have TAB'd into this field hit ENTER to bring up a list of all possible wait-for conditions. Use the arrow keys or mouse to select the wait-for condition. The conditions are as follows:
  
  Blank Line
  Select this top line for a continuation step. The Action of a continuation field will be executed after the line above it is executed.
  
  Default
  Default steps will be executed as soon as the State is entered.
  
  Message
  Wait for a message to be received. Enter the message number in the next field. Messages are described in more detail below.
  
  Timeout
  If no other wait-for conditions are met within the specified time, this step will be executed. Enter the number of 1/100 seconds to wait in the next field.
  
  Register = Zero
  Enter the register number in the next field. This step will be executed if the specified register/timer is or becomes zero during this state.
  
  Register <> Zero
  Enter the register number in the next field. This step will be executed if the specified register/timer is not zero.
  
  RTS
  When you have selected RTS, hit ENTER again to select ON or Off from a list. This step will be executed if Request To Send is or becomes equal to the selected polarity during this state. This option is only valid if you are emulating a DCE.
  
  CTS
  When you have selected CTS, hit ENTER again to select ON or OFF from a list. This step will be executed if Clear To Send it or becomes an equal to the selected polarity during this state. This option is only valid if you are emulating a DCE.
  
  DTR
  When you have selected DTR, hit ENTER again to select ON or OFF from a list. This step will be executed if Data Terminal Ready is or becomes equal to the selected polarity during this state. This option is only valid if you are emulating a DCE.
  
  DSR
  When you have selected DSR, hit ENTER again to select ON or OFF from a list. This step will be executed if Data Set Ready is or becomes equal to the selected polarity during this state. This option is only valid if you are emulating a DTE.
  
  DCD
  When you have selected DCD, hit ENTER again to select ON or OFF from a list. This step will be executed if Data Carrier Detect is or becomes equal to the selected polarity during this state. This option is only valid if you are emulating a DTE.
  
  RI
  When you have selected RI, hit ENTER again to select ON or OFF from a list. This step will be executed if Ring Indicator is or becomes equal to the selected polarity during this state. This option is only valid if you are emulating a DTE.
  
  Key Hit
  This step will be executed if the user hits any key on the PC keyboard. EMULATE will display 'Hit any key...' near the bottom of the screen.
  
  Error
  After hitting ENTER, hit ENTER again to bring up a list of possible errors. This step will execute if the selected type of line error occurs.
  
  ACTION
  After Tabbing to this field, hit ENTER to bring up a list of all possible actions. The selected action will be executed if the wait-for condition of this step is met. The actions are as follows:
  
  RTS
  After hitting ENTER, hit ENTER again to select ON or OFF from a list. Request To Send will be set to the selected polarity. This action is only valid if you are emulating a DTE.
  
  CTS
  After hitting ENTER, hit ENTER again to select ON or OFF from a list. Clear to Send will be set to the selected polarity. This action is only valid if you are emulating a DCE.
  
  DTR
  After hitting ENTER, hit ENTER again to select ON or OFF from a list. Data Set Ready will be set to the selected polarity. This action is only valid if you are emulating a DTE.
  
  DSR
  After hitting ENTER, hit ENTER again to select ON or OFF from a list. Request To Send will be set to the selected polarity. This action is only valid if you are emulating a DTE.
  
  DCD
  After hitting ENTER, hit ENTER again to select ON or OFF from a list. Data Carrier Detect will be set to the selected polarity. This action is only valid if you are emulating a DCE.
  
  RI
  After hitting ENTER, hit ENTER again to select ON or OFF from a list. Ring Indicator will be set to the selected polarity. This action is only valid if you are emulating a DCE.
  
  Good Message
  After hitting ENTER, enter the decimal message number in the next field. You must enter the message in the message dialog box (see Section 16.6). The message will be transmitted in the selected line protocol. If you are in BiSync, IPARS, or HDLC mode EMULATE will calculate and send CRC at the end of your message.
  
  Aborted Message
  After hitting ENTER, enter the decimal message number in the next field. You must enter the message in the message dialog box (see Section 16.6).
  This option is only valid in HDLC mode. The selected message will be sent but will be terminated with an ABORT sequence rather than a closing FLAG. This is often useful in testing the error recovery procedures of a circuit.
  
  Bad Message
  After hitting ENTER, enter the decimal message number in the next field. You must enter the message in the message dialog box (see Section 16.6). What constitutes 'bad' data depends on the data mode. In Async, the number of bits/character will be altered, causing parity and/or framing errors. In synchronous modes, the data is sent without a closing CRC, which may not really be bad data in some protocols. This option is often useful in testing the error recovery procedures of a circuit.
  
  Up Timer
  After hitting ENTER, enter the decimal register number in the next field. This option sets up a register as a timer that increments every 1/100 second. If the register has not been used in the program before you may assume its starting value to be zero, otherwise it will start incrementing from the last register value.
  
  Down Timer
  After hitting ENTER, enter the decimal register number in the next field. This option sets up a register as a timer that decrements every 1/100 second. The timer will not decrement below zero. You typically will set up the register with 'value' and 'store' actions before starting:
  
  

  State	Wait for:	Action:	Next	State
  1	Default	Value	100
  1		Store	1
  1		Down Timer	1	2

  
  Stop Timer
  After hitting ENTER, enter the decimal register in the next field. This action stops the selected timer and freezes it at its current count. This action is also combined with others in the S.T.C. action (see S.T.C. below).
  
  Increment
  After hitting ENTER, enter the decimal register in the next field. This action adds one to the value of the selected counter.
  
  Decrement
  After hitting ENTER, enter the decimal register in the next field. This action subtracts one from the value of the selected counter.
  
  Value
  After hitting ENTER, enter the decimal value in the next field. This action is used with the 'Store' action for presetting registers. See the example in 'Down Timer' above.
  
  Store
  After hitting ENTER, enter the decimal register number in the next field. This action loads the value set by the last 'Value' action into the selected register. See the example in 'Down Timer' above.
  
  Clear
  After hitting ENTER, enter the decimal register number in the next field. This action sets the selected register's value to zero.
  
  Tally
  After hitting ENTER, enter the decimal register number in the next field. This action sets up data for the histogram display (see Section 16.3). EMULATE calculates which bin the value of the selected register falls in and increments that bin by one. The value of the register is unaffected. This action is also included in the S.T.C. action below.
  
  S.T.C.
  After hitting ENTER, enter the decimal register number in the next field. S.T.C. is a combination of three actions, Stop a register, Tally its value, and Clear the register to zero. This combination is very useful in typical histogram data collecting programs.
  
  Display Reg.
  After hitting ENTER, enter the decimal register number in the next field. This action will display 'Register x = ' followed by the decimal register value near the bottom of the run time screen. Only one register may be displayed at the conclusion of the test. See 'EXECUTE' in Section 16.4.
  
  Display Msg.
  After hitting ENTER, enter the decimal message number in the next field. This action will display the selected message near the bottom of the run time screen. The message must not be longer than 40 characters (20 for CGA displays). This action allows the operator to track a test's progress without stopping the test.
  
  End Test
  When this action is reached the test ends and you are returned to the EMULATE menus. At this time you may display histogram results or display register contents. Note that if no 'Key Hit' wait for condition is active, hitting a key will also end the test.
  
  16.6 EDIT MESSAGES
  You edit messages by selecting 'Edit Messages' from the 'Edit' menu. At 'Message #:' enter the decimal number of the message you want to edit or create. If the message exists it is displayed, otherwise it will be created as you enter data. The message box consists of four lines. For simple messages, you will simply type the message into the first line. As you type you will see two lines of 'f's being displayed. This is the mask character, displayed in hexadecimal, with line 3 being the upper nibble and line 4 the lower order nibble. The mask character has no effect when you are transmitting a message. When waiting for a message, both the message character and the incoming character are AND'ed with the mask character before being compared with each other. This allows you to ignore unwanted bits such as parity bits, or to ignore whole characters in a message. Use the up and down arrow keys to move between lines, and the left and right arrow keys to move between characters in a message.
  The second line of the message box enables you to enter hexadecimal values for message characters. If there is a character on the second line then it and the character above it are interpreted as hexadecimal. Line one will be the upper nibble and line two will be the lower order nibble.
  To delete a character from the message, move down either of the mask lines and hit space. There is no way to insert characters, you must simply overtype with new characters.
  To delete an entire message, click on the delete button with the mouse, or hit down arrow until the delete button is highlighted and hit ENTER.
  Messages may be up to 1289 characters long. The message box scrolls sideways for messages that are longer than can be displayed.
  When you are done editing a message, hit up arrow to move you to 'Message #:' and enter a new message number. When you are done editing messages hit ESC key or click on 'Done' with the mouse.
  
  17.0 X.25
  
  The X.25 application decodes packets conforming to the X.25 protocol. X.25 is a recommendation of the CCITT and copies may be obtained through the United Nations bookstore:
  
  United Nations Bookstore
  Room GA 32B
  New York, NY 10017
  (212) 963-7680
  
  X.25 is rather complex and we must assume you have a basic knowledge of the protocol. Basically, however, X.25 is the packet mode interface to a public packet switch network. X.25 supports multiple virtual connections over a single physical link. At the link level, or level 2, X.25 uses a High-level Data Link Control (HDLC) type protocol to insure error free transmission of frames across the link. Packet level 3 allows for virtual circuit setup. The link level format can be decoded using the HDLC decode application. Also, the X.25 application decodes packets with the Q (Qualifier) bit according to recommendation X.25 for PADS (Packet Assembler/Disassemblers.)
  
  17.1 Running The X.25 Application
  The X.25 application is started by selecting it from the APPLICATION PROGRAM menu. The X.25 application can process live line data, captured data, or data from a journal file. The X.25 application forces the HDLC data mode so you do not need to select it before starting the application.
  The format of the screen that the X.25 application generates is described in Section 17.4. Briefly, though, the top half of the screen is the standard datascope format while the bottom half is a mnemonic decode of the frames displayed in the top half.
  The X.25 application handles live and captured data slightly differently. In live mode, the X.25 application continuously decodes the packets in real time. In captured mode (data in the capture buffer or from a journal file) the application decodes one packet each time the user hits a key. In captured mode you can move through the data with the arrow keys the same way you do when in Review Captured Data mode with no application program selected. When you next hit one of the non-arrow keys the X.25 application will decode the next packet (next Info frame) after the cursor. Note that the X.25 application will think the first bytes it sees are the address and control bytes, so you must move the cursor before the beginning of a frame or else ignore the first decoded packet.
  
  17.2 Live Mode
  In live mode the application is decoding live line data. There are three function keys active in live mode:
  F2
  Returns you to the PC Comscope II menus.
  F3
  Halts data capture and puts you into captured mode.
  F4
  Toggles display from selected display code to hexadecimal and back again.
  F10
  Same as F2.
  
  17.3 Captured Mode
  In captured mode the application is decoding captured data, i.e. data in the capture buffer or data from a journal file. In captured mode you step through the data one frame at a time and you can move back and forth in the captured data.
  The following keys are active in captured mode:
  F2
  Returns you to the PC Comscope II menus.
  F4
  Toggles display from selected display code to hexadecimal and back again.
  F10
  Same as F2.
  
  Arrow keys
  Home, Pg Up, Pg Dn, End - same as in Review Captured Data mode.
  17.4 Display Format
  When the X.25 application is running you will see a line across the middle of your screen that reads:
  
  LCN TYPE R S Q D M LNTH ==X.25 DEcode==
  
  Underneath this line will be the decoded information for each packet. Packet decode information is displayed in two colors: Receive data frames, i.e. frames generated by the DCE, will be displayed in magenta (red), and transmit data packets, packets generated by the DTE, will be displayed in cyan (blue). If you forget, notice that this corresponds to the color of the cursor block for the line the packet is on in the top half of the display.
  The X.25 application decodes the data in information frames, so you will notice the application skipping several frames until it comes to the next info frame.
  Underneath the 'LCN TYPE R S Q D M LNTH...' line will be up to seven lines of packet decode information. These seven lines are scrolled upwards with each new line of information. The last decoded packet will be the one immediately preceding the cursor in the top half of the screen.
  The decode information appears directly underneath the heading mnemonic as detailed below. Not all packets contain all of the fields listed below, and many packets will have additional information relevant to that packet.
  
  LCN - Logical Channel Number
  The decimal value of the logical channel.
  
  TYPE
  Mnemonic for the type of packet.
  
  R - Receive variable
  Can have values in the range 0 - 7.
  
  S - Send variable
  Can have values in the range 0 - 7.
  
  Q - Qualifier Bit 0 or 1
  Reflecting value of the qualifier bit.
  
  D - Delivery confirmation bit 0 or 1,
  Reflecting value of the delivery confirmation bit.
  
  M - More data bit 0 or 1
  Reflecting value of the more data bit.
  
  LNTH - Length
  Decimal value of the number of user data characters in a data packet (not including the header bytes).
  
  17.5 List Of Mnemonics
  The following is a list of all possible mnemonics for command or response type. These mnemonics are used under the 'TYPE' heading as explained in 'TYPE' above.
  
  CALA - Call Accepted.
  
  CALL - Call request will be followed by called and calling number.
  
  CLRC - Clear confirmation.
  
  CLRR - Clear request will be followed by a 'CAUSE:' indication:

  DTE originated
  Number busy
  Out of order
  Remote procedure error
  No reverse charging
  Incompatible destination
  No fast select
  Invalid facility request
  Network Congestion
  Not obtainable
  POA out of order

  or NOT defined may be followed by a 'DIAG:' indication. Diag codes are listed below .
  
  DATA - Data packet
  
  DIAG - Diagnostic packet will be followed by a 'DIAG:' indication. Diag codes are listed below.
  
  INTC - Interrupt confirmation.
  
  INTR - Interrupt packet.
  
  REJ - Reject.
  
  RESTART - Restart will be followed by a 'CAUSE:' indication;

  Local procedure error
  Network congestion
  Network operational

  or undefined may be followed by a 'DIAG:' indication. Diag codes are listed below.
  
  RESTART CONFIRMATION
  
  RNR - Receiver not ready
  
  RR - Receiver ready
  
  RSET - Reset logical channel will be followed by a 'CAUSE:' indication;

  DTE originated
  Out of order
  Remote procedure error
  Local procedure error
  Network congestion
  Remote DTE operational
  Network operational
  Incompatible destination

  or undefined may be followed by a 'DIAG:' indication. Diag codes are defined below.
  
  RSTC - Reset confirmation
  Undefined unknown packet type
  
  DIAG
  

  Code (decimal)	Meaning
  00	no additional information
  01	Invalid P ( S )
  02	Invalid P ( R )
  16	Packet type invalid
  17	Packet type invalid for r1
  18	Packet type invalid for r2
  19	Packet type invalid for r3
  20	Packet type invalid for p1
  21	Packet type invalid for p2
  22	Packet type invalid for p3
  23	Packet type invalid for p4
  24	Packet type invalid for p5
  25	Packet type invalid for p6
  26	Packet type invalid for p7
  27	Packet type invalid for d1
  28	Packet type invalid for d2
  29	Packet type invalid for d3
  32	Packet not allowed
  33	Unidentifiable packet
  34	Call in one way channel
  35	Invalid packet type for PVC
  36	Packet on unassigned LCN
  37	'reject' not subscribed to
  38	Packet too short
  39	Packet too long
  40	Invalid general format ID
  41	Restart w/no-zero 1-4, 9-16
  42	Bad packet this facility
  43	Unauthorized interrupt conf
  44	Unauthorized interrupt
  48	Timer expired
  49	Incoming call timeout
  50	Clear indication timeout
  51	Reset indication timeout
  52	Restart indication timeout
  53	Call deflection timeout
  64	Call set-up problem
  65	Facility code not allowed
  66	Facility parm not allowed
  67	Invalid called address
  68	Invalid calling address
  69	Invalid fac/reg length
  71	No logical channel avail
  72	Call collision
  73	Duplicate fac requested
  74	No zero address length
  75	No zero facility length
  76	Expected facility, not avail
  77	Invalid DTE facility
  78	Max number of redirects
  80	Miscellaneous
  81	Improper cause code, DTE
  82	Not aligned octet
  83	Inconsistent Q bit setting
  84	NUI problem
  96	Not assigned
  112	International problem
  113	Remote network problem
  114	International protocol prob
  115	International link out
  116	International link busy
  117	Transit network fac problem
  118	Remote network fac problem
  119	International routing problem
  120	Temporary routing problem
  121	Unknown call DNIC
  122	Maintenance action
  128	Network specific diag
  all others	Unknown diagnostic code

  
  18.0 HDLC
  
  The HDLC application decodes frames conforming to the HDLC format. Frames are delineated by special characters called flags. HDLC defines a zero-bit stuffing and removal technique that insures data will never appear as flag characters, so data in HDLC frames are always transparent. Each frame includes two CRC (error checking) bytes at the end. The first two bytes of each frame are defined as the address and control bytes. The HDLC application decodes the address and control bytes giving you a simple representation of their contents.
  The control byte can have up to four fields: 1-8 bits specifying the command or response, a poll/final bit, a 3 bit send frame number variable (0-7) and a 3 bit receive frame number variable (0-7).
  
  18.1 Running The HDLC Application
  The HDLC application is started by selecting it from the APPLICATION PROGRAM menu as described in the user's manual. The HDLC application can process live line data, captured data, or data from a journal file. The HDLC application does NOT automatically select the HDLC data mode, so you must do that before viewing live line data. The format of the screen that the HDLC application generates is described in Section 18.4. Briefly, though, the top half of the screen is the standard datascope format while the bottom half is a mnemonic decode of the frames displayed in the top half.
  The HDLC application handles live and captured data slightly differently. In live mode, the HDLC application continuously decodes the frames in real time. In captured mode (data in the capture buffer or from a journal file), the application decodes one frame each time the user hits a key. In captured mode you can move through the data with the arrow keys the same way you do when in Review Captured Data mode with no application program selected. When you hit one of the non-arrow keys, the HDLC application will decode the next frame after the cursor. Note that the HDLC application will think the first bytes it sees are the address and control bytes, so you must move the cursor to the very beginning of a frame or else ignore the first decoded frame.
  
  18.2 Live Mode
  In live mode, the application is decoding live line data. There are three function keys active in live mode:
  
  F2
  Returns you to the PC Comscope II menus.
  F3
  Halts data capture and puts you into Captured mode.
  F4
  Toggles display from selected display code to hexadecimal and back again.
  F10
  Same as F2
  
  18.3 Captured Mode
  In captured mode, the application is decoding captured data, i.e. data in the capture buffer or data from a journal file. In captured mode, you step through the data one frame at a time and you can move back and forth in the captured data. The following keys are active in captured mode:
  
  F2
  Returns you to the PC Comscope II menus.
  F4
  Toggles display from selected display code to hexadecimal and back again.
  F10
  Same as F2.
  
  Arrow keys
  Home, Pg Up, Pg Dn, End - same as in Review Captured Data mode
  
  18.4 Display Format
  When the HDLC application is running you will see a line across the middle of your screen that reads:
  
  LNT ADR TYPE PF R S/LNT ADR TYPE PF R S
  
  The left half (up to the '/') is for Transmit data, that is, frames generated by the DTE. The right half of the screen is for receive data, frames generated by the DCE. A receive frame that appears on the same line as a transmit frame ended after the transmit frame, so the display reads left to right, top to bottom. Aborted frames, frames with CRC error, and overlong frames will be displayed in color. The decode information may be nonsense in colored frames since you don't know where the error(s) occurred. Underneath the 'LNT ADR TYPE...' line will be up to seven lines of frame decode information. These seven lines are scrolled upwards with each new line of information. The last decoded frame will be the one immediately preceding the cursor in the top half of the screen. The decode information appears directly underneath the heading mnemonic as detailed below:
  
  LNT - Length
  Number of characters in the frame. The HDLC application supports frames of up to 500 characters. Longer frames will appear as two or more colored frames.
  
  ADR - Address
  Hexadecimal value of the first byte in the frame, the address byte.
  
  TYPE
  Mnemonic for the type of command or response.
  
  PF - Poll/final
  Value of the poll/final bit.
  
  R - Receive Variable
  Value of the receive variable (not present in all frames.) Can have values 0 - 7.
  
  S - Send variable
  Value of the send variable (present in info frames only.) Can have values 0 - 7.
  
  18.5 List Of Mnemonics
  The following is a list of all possible mnemonics for command or response type. These mnemonics are used under the 'TYPE' heading as explained in Section 18.4.
  
  INFO - Information frame
  
  RR - Receiver Ready
  
  RNR - Receiver Not Ready
  
  REJ - Reject
  
  SREJ - Selective Reject
  
  UA - Unnumbered Acknowledge
  
  SIM - Set Initialization Mode
  
  UI - Unnumbered Information Frame
  
  CMDR - Command Reject (or Frame Reject)
  
  XID - eXchange IDentification
  
  SNRM - Set Normal Response Mode
  
  S/DM - Set Asynchronous Response Mode or Disconnect Mode - depending on context
  
  SABM - Set Asynchronous Balanced Mode
  
  DISC - Disconnect Request
  
  UP - Unnumbered Poll
  
  RSET - Reset
  
  CFGR - Configure (SDLC)
  
  TEST - Test (SDLC)
  
  BCN - Beacon (SDLC)
  
  UNDF - Invalid Control Byte
  
  18.6 HDLC Statistics
  The Model 905 has the ability to determine line utilization in an HDLC or SDLC environment. This feature is called HDLC Statistics and is included with the optional HDLC Decode Software. Operation is described below.
  
  1. Select the HDLC data mode from the Comscope menus.
  
  2. Highlight or enter HDLCSTAT on the PROGRAM OPTION menu. Hit F9 to start the program.
  
  3. The HDLCSTAT program will prompt you:
  Report file name (ENTER for none):
  If you want the program to generate a report file, enter the name of the report file at this point. Simply hit the ENTER key if you don't want a report file.
  
  4. The program will then prompt you:
  Seconds between reports:
  Enter the number of seconds in each report period. The program will copy the screen to the report file (if selected) after each report period. The report totals (see below) are reset after each report period. You must enter a report period even if you are not generating a report file.
  
  5. The program will then prompt you:
  Minutes to run test (0 for continuous):
  Enter the number of minutes you want the test to run before stopping itself. If you want the test to run continuously, enter a zero.
  
  6. The test will then begin capturing and analyzing data. There are three groups of information presented: Line utilization, error rate information, and frame type summary. Each group is separated by a line '-------'s.
  
  6.1 The top section details line utilization. The INFO frames in HDLC are what carry data, so the number of bits in these frames can be used to estimate line utilization. The 'bytes' figures used here include the data characters, the address, and control bytes, the two CRC bytes, and one flag character for each INFO frame. The 'bytes' figure is then multiplied by 8 (bits/byte) and divided by the number of seconds to produce an equivalent BPS figure. This number can be compared to the bit rate of the data line to estimate the utilization of the line.
  The figures under 'DCE INFO' are for data coming from the DCE (receive data) and those 'DTE INFO' are for data coming from the DTE (transmit data). The figures on the 'Report' line are reset at the end of each report period, while those on the 'Cumulative' line are accumulated for the whole test.
  
  6.2 The second section provides a measure of line quality. The program accumulates the number of good, errored, and aborted frames. The Block Error Rate (BLER) is the ratio of errored + aborted frames may be due to line errors or generated by the DTE or DCE. Note also that this program will probably only catch data errors in one direction, since errors that occur between the end being monitored and the remote end will not be seen by the Comscope. You will however have some indication of these errors in the frame summary (below).
  
  6.3 The frame summary can provide information about the overall performance of the protocol and data line.
  For instance:
  

• The REJ and/or SREJ counts indicate data line errors.
  
• The ratio of INFO to RR frames provide an indication of line utilization.
  
• Mode setting commands (e.g. SNRM) may indicate equipment resets or gross line failures.
  
• RNR packets may indicate one end of the link is not keeping up with the other.
  
  18.7 Function Keys
  F2
  Freezes the display. The program does not update the screen until you hit F2 again, although the program continues to run. You may want to freeze the display when examining the accumulated numbers.
  F6
  Resets all the figures. F6 is the same as starting the test over, except that the report file and report period remain the same.
  F10
  Takes you back to the Comscope menus.
  
  19.0 The 'TERM' And 'FOX' Programs
  Two simple application programs are included with the Comscope. The source code for these programs is also included on the APPLICATIONS diskette and is a good starting point for those who want to write their own application programs.
  
  19.1 TERM
  The TERM program allows the Comscope to emulate a simple dumb terminal. It transmits keystrokes and allows the user to change that state of control leads. TERM does not emulate the display of a terminal but uses the standard Comscope live mode display to clearly show the data being sent and received. TERM is intended primarily for asynchronous mode, although it will operate in synchronous modes, send a one character data block (plus synchronization and CRC as appropriate) for each key struck. TERM can be very handy in bringing up new data circuit. You often do not know what control leads or data coding is required and the TERM program will let you rapidly experiment with different settings. TERM will work with either a DTE or DCE adapter.
  
  OPERATION:
  
  1) Connect the appropriate electrical adapter (DCE or DTE) and cable to the circuit under test.
  
  2) Select the data mode parameters, such as bits/character, parity, speed, etc.
  
  3) Select TERM from the APPLICATION PROGRAM menu and press F9 to start.
  
  4) The state of the control leads can be toggled with the following keystrokes (depress the Shift key and the indicated function key simultaneously):
  

  DCE adapter - DTE adapter
  Shift F1 CTS - RTS
  Shift F2 DSR - DTR
  Shift F3 DCD
  Shift F4 RI

  5) A break may be transmitted by depressing alt B (Depress the alt key and the 'B' key simultaneously).
  
  19.2 FOX
  The FOX program is a simple routine that transmits the familiar 'The Quick Brown Fox Jumped Over the Lazy Dogs back' message in the selected data mode. To operate, select the data mode parameters and then select FOX from the APPLICATION PROGRAM menu and press F9 to start. FOX will run with either a DCE or DTE adapter.
  
  20.0 What If It Doesn't Work?
  
  The PC printer mode can work with the Comscope in one of three modes (see Section 21.0 below.) Use the setup program that's part of your PC's BIOS to check that the printer port is setup in a mode compatible with the Comscope.
  Try forcing the Comscope to work in compatibility mode by using the following command line option:
  
  ega /n
  
  If you have more than 3 printer ports active on your PC, the BIOS will only recognize 3 of them, so you may have to enter the port address in the HARDWARE ADDRESS menu manually.
  
  Whenever you leave the HARDWARE ADDRESS menu (by hitting the left arrow key, for instance) the Comscope software will try to communicate with the Comscope unit. If you do not get a beep and a warning message on the bottom line, it means that you have successfully installed the Comscope.
  
  Is the Comscope turned on? (The On/Off button should be in the IN position).
  
  If you are running on battery, is the battery fresh and the A/C adapter removed from the Comscope?
  
  If the menus on the Comscope function correctly but the live mode display is nonexistent or garbled, your display adapter may not support the selected graphics mode. Note that some older graphics may produce "snow" when used with the Comscope. The speed requirements of the Comscope make it unfeasible to support the special requirements of these adapters. If you have a problem you will not be able to use the Comscope program.
  
  If you get a "NOT ENOUGH MEMORY" printout, you may have one of two problems.
  
  

• You actually do not have enough memory in your system - the Comscope needs approximately 256K to run.
  
• You have other programs or drivers resident in memory and there is not enough left for the Comscope program. Check your autoexec.bat and config.sys files for Terminate-and-stay-resident programs (like Sidekick) or device drivers that may need to be removed when the Comscope is running.
  If there are additional questions, call Telebyte for assistance at 631-423-3232, fax your questions to us at 631-385-8184, or email us at telebyteusa.com.
  
  21.0 Technical Notes
  
  The Comscope can communicate with your PC in one of three ways: Nibble, Byte, or EPP mode. The Comscope tries all three methods and uses the fastest one supported on your PC. The Comscope displays the mode it has selected in the lower right corner of the main menu screen. The three modes are:
  
  1) Nibble mode - In the original PCs the printer port was one directional, so a device like the Comscope must send data to the PC in 4 bit nibbles using the control lines. This is the slowest mode, but the mode that works with virtually all PCs. You can force this mode by starting the program with the /n command line option: ega /n
  
  2) Byte mode - Beginning with IBM's PS/2 computers, PCs began to support byte mode, when the data drivers could be turned off under software control so the Comscope can send data back to the PC in 8 bit bytes. However, even some PCs without the software control will work in this mode. If your main menu screen shows 'BYTE' in the lower right corner and the Comscope does not work reliably, you should either force the Comscope to run in nibble mode, as in 1 above, configure your PC printer port to true BYTE mode, sometime called 'bi-directional', or configure your PC printer port to EPP mode.
  
  3) EPP mode - This is a newer and more elegant option that allows the Comscope to run very fast. The PC can send a byte to or from the Comscope in a single machine cycle. If the Comscope is running in EPP mode, the main menu will display 'EPP' in the lower right corner.
  
  The PC does NOT use interrupts on the printer port.
  
  When you hit F9, the Comscope software downloads the appropriate .OM8 microcode file to the Comscope unit. The co-processor on the Comscope unit takes all line data, formats them into the Comscope internal format, and stores them in its internal ring buffer. The Comscope software reads these data in through the printer port, copies them to the PC capture buffer, and displays them on the screen. When there is no more data from the Comscope unit, that is, the Comscope software has 'caught up' with the line, the Comscope software will sample the control leads (if control lead capture is not enabled), check for a key having been hit, generate a time stamp (if selected), and write data to the journal file (if selected). The software has been designed with this two-layer approach to enable the Comscope to monitor much higher data rates than would be possible otherwise. Most real data lines contain idle time when the Comscope can 'catch up,' so the Comscope will typically handle higher data rates than the specifications suggest. However, you should be aware of some of the implications of this approach:
  
  
• at higher data rates the display may lag the actual line data somewhat. This is normally not a problem since your eye cannot follow the data that closely at high rates anyway.
  
• the frequency at which the lowest software level executes will be reduced at higher data rates. This means that the time stamp resolution will be lower and changes in control leads may not be displayed as rapidly. You may also note a lag in the response to the keyboard if you hit one of the function keys.
  
• if journaling is selected it will slow down the overall rate of display. If you are journaling to a floppy or if your hard disk file is very fragmented this delay may be significant.
  The Comscope has an internal table of all display mnemonics. The display code files contain a table that identifies which display mnemonic to use for each data character. They also contain a table translating each keyboard code into the appropriate value for that code. This is used in the trap menu to set the actual value to search for if a trap on data characters set (Sections 11.7 and 11.8). This is also used in the PROGRAM OPTION mode to translate Comscope generated data to the selected display code characters.
  The simplest way to identify the actual character represented by a particular mnemonic is to hit F4 to toggle to hexadecimal display.
  
  REQUIREMENTS & SPECIFICATIONS
  
  
• PC, PC XT, PC AT, 386, 486 machines. Requires one free printer port.
  
• CGA 320 x 200 video mode (not monochrome). Supported by CGA, most EGA and VGA cards. EGA mode is supported by EGA and VGA cards. MONO mode supports IBM compatible monochrome displays.
  
• requires no internal slots
  
• requires approximately 256K free memory
  
  PROTOCOLS: asynchronous: 5 - 9 bits/character even, odd, none parity
  
  
• CRC - 16 on 7 or 8 bit synchronous data generation
  
• CRC - 6 IPARS generation and checking 6, 8, 12, or 16 bit synchronization sequences selectable pad (idle line) character most significant or least significant bit first normal or inverted data
  
• bit oriented (HDLC)
  
• 5 - 8 bits/character
  
• standard HDLC CRC checking
  
• NRZ, NRZI (clocked or derived)
  
• unknown (transparent):
  
• 5 - 8 bits/character
  
• external or internal clocking
  
• most significant or least significant bit first
  
• normal or inverted data speeds: any integral multiple of 7.3728 MHz
  
• Power: AC via supplied adapter
  
  22.0 Help
  
  Assistance can be obtained by visiting our Technical Support Center.
   

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  Comscope is a trademark of Telebyte
  
  Telebyte grants the original purchaser of this product the right to make several copies of the program as long as the copies are used exclusively with the Comscope purchased with the software or to analyze data files captured with the Comscope. You are also authorized to make several copies of this manual as long as the manual is copied in its entirety and this copyright notice is included as a permanent part of the copy.
  
  Radio Interference
  The Comscope is classified as test equipment and is not intended for residential use. While normal practices have been followed to preserve the shielding integrity of the computer to which this product is connected you should be aware that the Comscope is not certified by the FCC to conform with Class B or A emission limits for computing devices. Note that the cable mounting screws should be tightened securely to insure electrical contact.
   

  ---

  
  Warranty
  
  Telebyte warrants the equipment to be free from defects in material and workmanship, under normal and proper use and in its unmodified condition, for 12 months, starting on the date it is delivered for use. TELEBYTE's sole obligation under this warranty shall be to furnish parts and labor for the repair or replacement of products found by TELEBYTE to be defective in material or workmanship during the warranty period. Warranty repairs will be performed at the point of manufacture. Equipment approved for return for warranty service shall be returned F.O.B. TELEBYTE factory and will be redelivered by TELEBYTE freight prepaid, except for non- continental U.S.A. locations. These deliveries will be sent COD freight and import/export charges.
  
  THE ABOVE WARRANTY IS IN LIEU OF ALL OTHER WARRANTIES, EXPRESSED OR IMPLIED, STATUTORY OR OTHERWISE, INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. TELEBYTE SHALL NOT BE LIABLE FOR ANY DAMAGES SUSTAINED BY RESELLER OR ANY OTHER PARTY ARISING FROM OR RELATING TO ANY EQUIPMENT FAILURE, INCLUDING, BUT NOT LIMITED TO CONSEQUENTIAL DAMAGES NOR SHALL TELEBYTE HAVE ANY LIABILITY FOR DELAYS IN REPLACEMENT OR REPAIR OF EQUIPMENT.
  
  Out of warranty equipment may be returned to the Greenlawn, NY customer service facility prepaid as described above. Return shipping charges will be billed to the customer. The repaired unit will have a 90 day warranty. In those cases where "NO TROUBLE" is found, a reduced charge will be billed to cover handling, testing and packaging.
  
  Whether in or out of warranty a Return Material Authorization number (RMA) is necessary. Assistance can be obtained by visiting our Technical Support Center.

  Document No. 0315-/Rev. -