24 Apr
2007
24 Apr
'07
8:37 a.m.
Allison schrieb:
The question on junkbox z80 systems made me remember
that
old 386 and 486 system besides providing a raft of 32kx8 SRAMS
also had a keyboard interface chip..
I have a few salvaged 8742(smae as 8242) from PC hardware
of the AT class 80386-486 level.
Without resorting to eraseing the Eproms (8742) and reprogramming
them I've wondered if..
Can these parts (PC AT keyboard interface) can they be used for
small system as a interface from AT or PS2 keyboard to a 8bit micro.
Right off I suspect yes. However is there any information on how
to "talk" software wise to them as to what kind of results and
commands they take?
See http://www.arne.si/~mauricio/kbdfaq.html for abundant information on
the keyboard,
and programming the controller. Basically, you connect it to a z80 the
same way as it is done
in the PeeCee - wire it to i/o port 60/64h and use the same logic to
program raw commands.
Normally, in homwbrew systems, people tend not to use a 8042 pulled from
a scrap board but talk
to the keyboard directly, through the serial protocol described above.
The keyboard itself typically
contained some 8048 controller to scan the kbd matrix.
I don't have the exact circuitry for the 8042 UPI at hand right now, but
the schematic can be
found in the IBM AT Technical Reference Manual.
--
Holger
P.S.: Hopefully this will get through to the list, as the listmaster rejects RFC compliant
digitally signed S/MIME mails :-(((((((