"Howard Goldstein" wrote
Gene Storey wrote:
: this modem was based on an old CP/M machine

How so?

You'll see lots of TNC source code start at 0x0100 for development.
The Z-80, and I/O on the TNC-2 were all common to CP/M machines.

I developed C programs on my H-89 for TNC-2 for 10 years. My last
project was a port of parts of Xinu on the DRSI TNC-2 modem from
my H-89 CP/M machine.

Ah--C/80 from Software Toolworks! I think I paid $20 bucks for it, and
sold about $20,000 worth of software using it (non-Ham). Alas, my H-89
CRT blew out before the computer did, so I interfaced a Micromint Apple
Sprite Video card (cut off the Apple bus, drilled holes for wires, and super-
glued it into a rectangular hole made into the H-89 development board),
and hooked it up to my TV. 40 characters wasn't the same as 80 though
(once you've seen speed and line length, there's no going back :-) The
color and sprites were neat though. Finally broke down and bought an
IBM clone with a flip-top case, running 4.88 MHz (used that until 1993
when I bought a honkin 66 MHz motherboard!) That's about the time I
got into ISDN routers and really started making money...