This program is meant to be executed as a "live program" from a BBS system and as an "external protocol" from a remote-user's communications program. It will display in~formation concerning the quality of the transmission channel existing between the remote user and the BBS system. It may be helpful in obtaining better quality service from the telephone company.
Now to install this program.
If you are a BBS system operator, you create a batch file containing the following information:
REM * Noise Program Batch file *
D:\PATH\NOISE/PORT=2/MODE=MIRROR
| | | | |____ Execute in mirror mode
| | | |________________ COM port (1-4)
| | |_______________________ Program name
| |_____________________________ Path to program
|___________________________________ Drive name
You then define this as a "live program" (DOOR) in your BBS
system software configuration.
If you are a remote-user, using a communications program like TELIX or PCPLUS, you create a batch file containing the following information:
REM * Noise Program Batch file *
D:\PATH\NOISE/PORT=2
| | | |
| | | |________________ COM port (1-4)
| | |_______________________ Program name
| |_____________________________ Path to program
|___________________________________ Drive name
You then define this batch file as an "external protocol" DOWNLOAD utility. In TELIX, you use ALT-O to get to the cor~rect menu. You can use "NOISE" as the protocol name. Tell TELIX that you do NOT wish to be prompted for a file name.
How to use this program.
Find a BBS system that has this line-noise live program "door" installed. Execute the live program from your com~muni~cations program just as though you were going to execute any other live-program. When the BBS system advises that you execute your local NOISE.COM program, just hit the "down~load" key (PgDn for TELIX) and select "NOISE". The program should begin execution and keep a running tabulation of the amount of data sent and received, the number of bad bytes and the percentage error-rate.
When you wish to exit the program, just hit control-break or control-C. Control-break is "cleaner" because it doesn't mess up your screen with a "^C" echo and cause the screen to be overwritten.
You can also execute this program from the DOS command line. If you were executing a communications program, you could "shell" to DOS and execute the same command-line that you used within the batch file. If your program exists within the current path, you need not type the path and drive on the command line. If the communications adapter port in use in COM1, you need not enter anything on the command line. In this case, "NOISE", entered at the DOS prompt or from the batch file, is sufficient.
Other usage:
NOISE has two modes of operation. The default mode is to send a string of bytes to a remote location and record any errors in the string being echoed back. The other mode, the "mirror" mode, simply echoes any characters received. It functions as though you put a connection between pins 2 and 3 of a RS-232C connector to immediately echo any bytes re~ceived on the RX line back to the TX line. The only differ~ence between NOISE in the "mirror" mode and a piece of wire is that if NOISE receives a ^C, it aborts. You can see from this that NOISE can be very useful in debugging local RS-232C connections as well as monitoring line-noise.
NOISE.ARC contains the complete source-code and documen~ta~tion. The source code shows how to operate the UARTs used in IBM-compatible computers in interrupt-mode. Interrupt-mode operation is necessary if you intend to use these UARTs at speeds much in excess of 2400 baud for communications. In particular, the code shows how to:
(1) Set up the required interrupt vectors.
(2) Set up the UART
(3) Set up the interrupt controller.
(4) Operate both transmit and receive in interrupt-mode.
(5) Trap ^C and control-break so vectors may be restored.
(6) Restore interrupt vectors before program exit.
(7) Restore interrupt-controller mask program before exit.
(8) Restore saved UART parameters before program exit.
Restoring the machine-state before the program exits is very important. The major failing of many, otherwise excellent, home-made communications programs has been that the program may exit without restoring the machine state. The next time a program is executed, the system will crash if the machine state has not been correctly restored.
If you use these routines for a tutorial, remember that it is seldom necessary to operate the UART in interrupt-mode for transmit, only for receive. Operation of the UART in inter~rupt-mode during transmit will accomplish nothing use~ful in a communications program since the program must wait until the host receives the characters, processes them, and sends back a response, before the interactive user sends more characters. Operation in interrupt-mode for receive is important so that no incoming characters are ever lost even if the user is typing at the keyboard, reading from a file, etc.
How the program works.
The program sends a string of all the ANSI characters (with ^C missing) to the remote computer. The remote computer simply echoes these characters back.
The program then compares the characters sent with those received. If they are the same, the block-number and byte-count is updated on the screen and the cycle continues. If a byte is missing or garbled, the program records this fact, calculates a running error-rate, and then continues. The process continues until aborted by the user or until the modem carrier fails.
If the user aborts, a string of ^C characters are sent to the remote computer to cause the remote program to abort also. In case of an abort for any reason, the machine-state is restored before the program terminates.
Warranty.
This program is supplied "as-is" with no warranty what~so~ever. The complete source-code is provided so the users may determine for themselves if the program may serve a useful purpose.
