Re: Need help with A2 mystery boards

[nparker@cie-2.uoregon.edu (Neil Parker)]

In article <53pcbh$6oq@login.freenet.columbus.oh.us>
dalloff@freenet.columbus.oh.us (Dave Althoff) writes:
>Robert Sutton (sfyfsi@scfn.thpl.lib.fl.us) wrote:
>[...]
>: ----------
>: Networker
>
>: Zoom Telephonics, Inc.
>: (C) 1983
>
>: ASSY NO 5050503-001
>: REV S/N
>
>Not familiar with it.  Sorry.

I believe this is an old 300 baud modem.  I've never actually seen one, but
judging by the descriptions in an old terminal software manual I have lying
around, it's a pretty primitive piece of hardware--no auto-dial or auto-answer
capability at all...you have to dial manually, and flip a switch from "off"
to "originate mode" when you hear the carrier tone.

For whatever it's worth, the card is apparently built around a Motorola
6850 serial chip, mapped into memory at $C0nE and $C0nF (where "n" is the
slot number plus $80).

>: ----------
>: Softcard
>
>: Microsoft
>: (C) 1981
>: s/n: E054223A
>
>: Has a Z80A CPU, 4 dip switches and a red "CARD ON" LED
>
>That's a CP/M board.  In fact, I have one around here somewhere, but no
>software for it.

Somebody else posted the switch settings recently, so I'll pass on that
part.

To start the Z80 running, write to $Cn00 (where "n" is the slot number).
This suspends the Apple's CPU (so there had better be valid Z80 code at Z80
memory location 0, which normally corresponds to 6502 memory location
$1000).  Subsequent writes to $Cn00 (or $En00 in Z80 mode) toggle back and
forth between the Z80 and the 6502, with each resuming wherever it left off
before.

The only software I know of that uses this card is Microsoft's Softcard
CP/M operating system, and clones thereof.  Without Softcard CP/M, the
board is pretty much useless.

               - Neil Parker
-- 
Neil Parker, nparker@{cie-2,cie}.uoregon.edu, http://cie-2.uoregon.edu/~nparker

     "Evolution is vastly overrated."  -- Ambassador Delenn, _Babylon_5_