18 Nov
2007
18 Nov
'07
7:44 p.m.
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
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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.