5 May
2021
5 May
'21
1:03 a.m.
-----Original Message-----
From: Tony Duell [mailto:ard.p850ug1 at gmail.com]
On Wed, May 5, 2021 at 8:12 AM Paul Birkel <pbirkel at gmail.com> wrote:
Remember that the 8039 has separate program and data memory spaces.
"Sokath, his eyes uncovered." Thank you Tony. Your notation observations both
sound very reasonable to me.
paul
-----Original Message-----
From: Tony Duell [mailto:ard.p850ug1 at gmail.com]
The straight-thru wiring on ~RD and ~WR alongside ALE with no address decoding is IMO
rather odd. I wonder how that design actually works (either assumes that it is the only
writable
device present, or actually latches 8 bits of address and shadows some valid ROM address)
and then what gets written to the encoder for what purpos(es). On Tue, May 4, 2021 at 10:33 AM Paul Birkel via
cctalk <cctalk at classiccmp.org> wrote:
The GI encoder is a DIP-40 labeled as "321239007 M2406-054-02 GI 8233 CBU
TAIWAN". I seek technical documentation for this IC.
You might take a look at the manuals here :
http://cpu-ns32k.net/Whitechapel.html
I am pretty sure there's a keyboard techincal description in 'binder
1' and a reverse-engineered schematic in 'binder 2'. While it's not
quite the same IC, it's related and the power pins are in the right
place :-)
Alas there is no real description of what that IC does or how to talk
to it from the 8039. It is designed to sit on the 8039 bus, it takes
in the multiplexed address/data bus, ALE, rd/ and wr/