A TNC is a Z80-based single-board computer which is connected to the RS-232 circuitry of a computer. It has a small on-board modem and a Z80 core with memory and SIO. The Z80 runs a program that implements the AX.25 protocol used in amateur packet radio. If used with a PC, the PC runs just a plain vanilla terminal program to view the TNC's text output - a waste of computing power.

The BayCom terminal software no longer requires a TNC - a simple modem or a slotcard is the front-end, and all AX.25 functions are performed by the BayCom software on the PC.

This saves the cost for the TNC. The BayCom USCC slotcards are also more powerful than a TNC, because they are directly connected to the ISA system bus and do not have to exchange data via the RS-232 port.

The BayCom DOS software consists of two programs: a "TNC" and a "Terminal".

The "TNC" (called L2) runs in the background as a memory resident routine under DOS, which permits other programs to run simultaneously. A remote station can connect to it just like to a TNC.

All text left by the remote station is shown on the screen when the terminal program (called SCC) is started. Note however that SCC is neither a PMS nor a BBS system - any messages left are just text on your screen.

The terminal itself is used as command tool to control connections and to exchange text with the connected stations. The screen is split into three windows, similar to SP and other terminal programs. The upper window is for outgoing data and commands, the middle window is for incoming data, and the bottom window is used to monitor the frequency.

There are a lot of other functions making packet radio operation very comfortable. Examples include scroll-back in every window, multiconnect properties on switchable screens, support for EGA and VGA video modes, password and remote control functions.

THE FILES

The software package (the current version is 1.60) consists of several program and data files:

L2.EXE

the central program unit of the BayCom system - the "TNC" substitute. It runs as a terminate-and-stay-resident (TSR) routine in memory, which means that once you have started the program, you will be returned to the DOS prompt. The only indication of L2's presence is a flashing rectangle in the upper right corner of the screen. Provided modem and radio are connected, your computer will behave on air as if it was a standalone TNC. Other stations can connect to you and write text to your screen, which you can see once you start the terminal program (SCC.EXE). When only L2 is running, the computer may be used for other jobs such as programming, word processing etc. The only restriction is that L2 needs about 90kB of the available memory, which leaves less memory to other applications. On a standard IBM machine with 640kB DOS memory this amounts to a reduction to 550kB, which may lead to problems with larger applications.

SCC.EXE

the terminal (user interface). After starting SCC.EXE, you will be presented with the usual three-window screen. It enables you to conduct full packet radio operation.

OFF.COM

this little program removes L2.EXE from memory and releases its memory to other applications. Having other memory resident (TSR) routines (e.g., Norton Commander) may cause problems as the memory freed by OFF.COM may not be returned to DOS immediately.

SCC.INI

this is the configuration file. It is a normal ASCII text file and contains all the default parameters entered by the user and can be edited with a normal text editor (such as, e.g., EDIT under DOS). Some of the parameters are set with INSTALL.EXE. However, you can also set parameters from the terminal, and we recommend that you edit the file later if you want to make parameter changes permanent. SCC.INI is compiled intop something more computer-readable by the parameter compiler PARA.EXE. Whenever PARA.EXE gets called, all changes entered from the terminal disappear. This happens automatically whenever L2 deems SCC.PAR to be older than SCC.INI (just like most amateur computers you can be guaranteed that this will happen the first time you fire the program up in 2000), or when SCC.PAR is damaged. SCC.INI is initially created by INSTALL.EXE.

PARA.EXE

the parameter compiler. It takes the parameter data from SCC.INI and converts it into a machine readable form, which is stored in the file SCC.PAR. PARA.EXE can be invoked manually, but is called automatically after each start of L2.EXE when SCC.PAR is older than SCC.INI, or when SCC.PAR doesn't exist. When it encounters an illegal parameter, PARA will produce an error message. It will also check whether the specified hardware (COM port or SCC card) actually exists. If not, the software is automatically configured for COM1. PARA must also be called if the hardware configuration has been changed (e.g., by adding a USCC card) or when a new password has been installed. Another application of PARA is the compilation of the help file TERMHELP.SCC.

SCC.PAR

the parameter file generated by PARA.EXE. It is best left alone, so don't tamper with it manually. If it is missing on your release disk, don't worry, it will be created automatically.

 

TERMHELP.SCC

the help file. It is a text file and contains the help texts you can call up with :HELP from the terminal screen.

SCC.VID

the screen data cache. BayCom can save screen contents automatically when you exit the teminal and restore the screen when you return to the program. The screen data is saved in SCC.VID and retrieved when the program is started the next time. SCC.VID is created when SCC.EXE is first started.

SCC.PWD

the password file for the automatic generation of sysop passwords and the remote login via the //j command. If you need remote login capabilities, you must generate this file.

BAYCOM.BAT

a simple batch file that starts L2.EXE, then SCC.EXE, and removes L2 from memory with OFF.COM once you have left the program. It is intended for users who are not interested in memory resident operation of L2.

INSTALL.EXE

the installation program. It is self-explanatory.

SCC.LOG

all log data from the packet station goes into this file, which is generated by the program if the LOG function is ON

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