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- TFLINK 1.0 Archive Notes - G0FRD, 4th Nov 1996
- ----------------------------------------------
-
- Introduction
- ------------
-
- TFLINK is a DOS program to allow a DOS PC running TFPCX (or
- equivalent) to emulate a packet radio TNC on behalf of another host
- computer system (for example, Linux). It does the much same job as
- PCTNC (DG3VT/DL2ECK), and TNCEMU (EB7CJO). Unlike both of these,
- however, TFLINK is a TSR program, so you can do other things on the PC
- that is emulating a TNC (for example, play Tetris).
-
-
- Archive contents
- ----------------
-
- The TFLINK10.ZIP archive contains two further zipped archives;
- TFLNKBIN.ZIP, and TFLNKSRC.ZIP.
-
- TFLNKBIN.ZIP contains the TFLINK.EXE TSR program itself, a minimal
- documentation file TFLINK.DOC, and a test program TFTERM, which you
- can use if you intend to use Linux (or a closely related UNIX) as the
- host system to connect to your TNC-emulating DOS PC.
-
- TFLNKSRC.ZIP contains full 'C' source code and a makefile to build
- TFLINK.EXE. As my DOS system has expired, it is unlikely that I will
- be developing TFLINK any further, so if you want to take the source
- and use it, modify it for your own ends, or improve it, then here it
- is. The original was built with Borland Turbo-C.
-
-
- Additional notes on running TFLINK.EXE
- --------------------------------------
-
- On slower DOS systems (286 12MHz is the slowest I have), I found that
- I had problems running just TFPCX on the system, and that TFLINK and
- TFPCX would not coexist at all. This was tested with several versions
- of DOS, from 3.3 to 6.2, with no major differences. The symptoms were
- that the system would either lock, or print some form of overflow
- message and then lock. The solution was to use a lighter-weight form
- of TFPCX - TFX_UART version 2.7 from the TFX.ZIP archive worked fine
- on all test systems (the only noticable difference is that it reports
- itself as version 82.7 rather than 2.7 when queried by TFLINK).
-
- TFLINK requires only three lines in the serial cable to be connected -
- TXd, RXd, and Ground.
-
- The undocumented -R flag sets TFLINK to read-only mode; that is, it
- will send characters from TFPCX to the host system, but not from the
- host system to TFPCX. This was to effectively disable transmit when
- testing, but since this also inhibits TFPCX setup commands such as "m
- uisc" from being sent from the host system, it isn't all that useful.
-
- On Linux (if you have it), TFTERM behaves better in a standard
- multiscreen that it does in an X window. This is probably something
- to do with the way it manipulates stty settings. It's only a test
- program, in any case.
-
- TFLINK has only been tested with Tnt (version 0.9l) under Linux. It
- should however also work with other non-Baycom terminal program and
- operating system combinations, since it enables emulation of a general
- purpose and hostmode TNC.
-
-
- Further work on TFLINK
- ----------------------
-
- The unload command is rather haphazard. It should really use a DOS
- INT to communicate to the TSR that it should terminate, but in fact it
- just sets a bit in the PIC chip to 'unlock' the serial port, relying
- on the background TSR to spot this at the next timer interrupt. The
- 'foreground' TFLINK doesn't even check that the TSR has in fact
- unloaded - it just assumes everything will be fine.
-
- When the TSR terminates, it doesn't check to see if another TSR has
- been loaded after it that may have redirected one if its vectors.
- This can result in a system crash if you don't unload any TSRs loaded
- after TFLINK, before unloading TFLINK itself.
-
- Too much code is held resident in the TSR. For example, the command
- line argument processing can be discarded just before the program
- installs itself as a TSR; this will save memory.
-
- Flow control on the serial link to/from TFLINK is something that
- hasn't been full investigated (happily, the WA8DED hostmode protocol
- seems to take care of most of this, though).
-
- A foreground debugging/tracing mode for TFLINK.EXE would be nice.
-
- After all the messing about with UART and PIC registers, creating a
- TSR, etc, is done with, the program is embarassingly simple.
-
-
- Disclaimer
- ----------
-
- TFLINK.EXE and its source code are provided free of any charge for
- amateur and non-commercial use. Within this constraint, you may do
- anything you like with the code except claim that you wrote it.
-
- There's no warranty, or guarantee that it will do what you want, or
- even what it claims to do.
-
-
- Acknowledgements
- ----------------
-
- Finally, thanks to the author and translator from Pascal to 'C' of the
- IBMCOM serial comms source code package, for doing over half of the
- work of TFLINK.
-
-
- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
- G0FRD | AX25 BBS Packet - G0FRD @ GB7BEN.#43.GBR.EU
- Simon Baldwin | AMPR.NET TCP/IP - g0frd@g0frd.ampr.org
- Leighton Buzzard | INTERNET at work - simonb@sco.COM
- Beds (IO91PV, SP92) | INTERNET at home - Probably never
- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~