[aprssig] What is "TNC Channel Switching"?

Greg D ko6th.greg at gmail.com
Sat Apr 12 17:54:26 CDT 2014

Stephen H. Smith wrote:
> On 4/12/2014 1:55 PM, Greg D wrote:
>> Stephen H. Smith wrote:
>>> However, many users still use the command-line mode instead, since 
>>> many older
>>> TNCs don't support KISS.   (Particularly the MFJ 127x series TNCs that
>>> crammed in numerous other modes, so that there wasn't enough room in 
>>> the
>>> 27256 eprom for KISS support.  I have replaced the OEM firmware on 
>>> countless
>>> MFJ 127x TNCs with the final release "official" TAPR 1.1.9 firmware 
>>> precisely
>>> to regain the KISS capabilities.)
>> Um, I have an MFJ 1278T TNC, and am running it in KISS mode under 
>> APRSIS/32.
>> Stock firmware on it, I believe, though I don't recall what version.
>> Greg  KO6TH
> That's a relatively late version of the MFJ-1270 family that (I think) 
> finally went to 27512 EPROMs instead the '256s of earlier versions and 
> consequently has a lot more room for code.
> The original MFJ-1270 and the MFJ-1274 that I still have came OEM with 
> KISS-less firmware.    I put the generic last-ever TAPR TNC2 V1.1.9 
> firmware in both instead, to regain the KISS mode.
> (I also hacked the eprom image to make the device power up defaulted 
> to full 8-bit 8-N-1 instead of the archaic default 7-E-1 serial port 
> settings, avoiding having to constantly init with AWLEN 8, 8BITCONV 
> OFF and PARITY 0.)
Yeah, I thought of that (being a more recent product).  The unit was a 
club "white elephant sale" acquision (pedigree unknown), and has been 
working fine.  It replaced a Baycom-type setup that stopped working 
after upgrading my PC from DOS through Win95 to Win98SE and ultimately 
to Linux many years ago.  It came with the 2400 BAUD modem option board, 
which is pretty much useless.

KISS mode seems to be sticky across power cycles, so I don't need to do 
anything special.  It just works.

Greg  KO6TH

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