> -----Original Message----- > From: Tony Duell [mailto:ard.p850...@gmail.com] > > On Wed, May 5, 2021 at 8:12 AM Paul Birkel <pbir...@gmail.com> wrote: > > > > > -----Original Message----- > > > From: Tony Duell [mailto:ard.p850...@gmail.com] > > > > > > > On Tue, May 4, 2021 at 10:33 AM Paul Birkel via cctalk > > > > <cctalk@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/ > > > > 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). > > 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
