Homebuilt S-100 TRS-80s - initial report

From: Dave Dunfield <dave04a_at_dunfield.com>
Date: Wed Jan 12 22:53:45 2005

Hi Guys,

Well --- I played with these two machines this evening.
Case anyone missed my original posting - as part of a sizable load
of equipment I picked up this past weekend, I received two homebrew
S-100 systems which are reported to be complete implementations
of a TRS-80 on S-100 cards.

They had been stored for a long time in a cottage, so they were
quite dirty (fortunately no evidence of mice!) - Removed all cards,
cleaned up the slots and connections, checked out the power supply,
reinserted the cards, hooked up a Zenith monitor and fired the
first one up...

Immediately got a "Cass?" prompt, then "Memory size?", and finally:

Radio Shack Model III BASIC
.... normal Model III stuff ...

yup - the thing actually works!

This one has:
  WAMECO CPU-2 Z80 CPU card
  SSM VB1B video card, with fairly extensive modifications, presumably
    to make it TRS-80 video compatible.
  A standard S-100 memory card (didn't write the type down).
  A homebuilt card which has EPROM copies of the TRS-80 ROMs, as well as
  a fair bit of logic, speaker circuit, keyboard interface --- I would
  guess "Everything else" from the TRS-80.

So, I moved on to the second one - this one has the same cards as the
one above, plus a homebuilt disk controller card. Cleaned it up, checked
the supply, powered it up and --- NOTHING!

Then I remembered that you need to hold BREAK at reset/power-up on TRS-80s
with disks to get to ROM basic ... Tried holding BREAK and voila! - same
prompts as above!

So, I hooked up the drives, powered on - sure enough, Drive 1 came on...
Put in a TRS-DOS disk for the Model III, and hit reset --- Next thing
I know, I'm in TRS-DOS, running exactly like a Model III.


As Sellam put it so eloquently ... this things are effing cool!

Will take pics this weekend, and try to get them (and more of the new stuff)
on the site sometime next week - will post a notice when ready.

dave04a (at)    Dave Dunfield
dunfield (dot)  Firmware development services & tools: www.dunfield.com
com             Collector of vintage computing equipment:
Received on Wed Jan 12 2005 - 22:53:45 GMT

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