19 Nov
2007
19 Nov
'07
7:07 a.m.
Date: Sun, 18 Nov 2007 23:47:32 -0500
From: rescue at hawkmountain.net
To:
Subject: Re: what the heck is it
dwight elvey wrote:
The FDC board has two 34 pin connectors... labelled 0 and 1. One
connector for each of the two floppy drives. I thought that a perculiar
arrangement, as one connector should be able to support 2 to 4 drives.
Both floppy drives are configured as drive 0.
No other (HD) connectors on the floppy interface board.
Hi
It is most likely was an unusual disk format. Chuck mentioned
M2FM. This is quite likely. Many of these special purpose machines
had their original software developed on MDS800's. At the
time, double density disk formats hadn't been tied down and M2FM was as
likely as any of them. They most likely had some previous
machine with this format and wanted to keep this format
for compatability.
I'd think it would still be worth bringing up CP/M on it.
There are a few people that have M2FM on their MDS800's
that could help.
The keyboard is most likely a parallel type as well.
It would be a chalanging project but the amount learned
would make it worth the time.
Dwight
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From:
cclist at sydex.com
On 18 Nov 2007 at 11:00, Curtis H. Wilbar Jr. wrote:
It sure would be overkill unless it was to be used with some
non-standard format. If there are some WD chips on the
board, it might be a combination board as you suggest.
Still I suspect a special format.
Dwight
3 large chips on the FDC board...
N8X305I
N8X330N
N8X320N
Signetics bipolar microcontroller stuff. Very interesting in that the
8x330 is used--it's the floppy controller of the series; you don't
run across them very much. It's designed to interface with the 8x300
series and nothing else.
The 8x320 is the register array usually used to interface the 8x300
to external systems. You should probably find some bipolar RAM and
ROM there also as well as some I/O ports (8T32/8T36).
What makes this unusual is that it's found on an 8085 system with
5.25" floppies rather than a traditional MOS FDC. Were this only for
floppies, this definitely would have been a ridiculously expensive
implementation for the time (and power-hungry). However, I wonder if
that board doesn't also have a hard disk interface connector (e.g.
SA4000) which would have been right for the time--and made sense.
Is there an EPROM for the 8085 on the main board? If so, have you
dumped it? It might clinch the identification.