14 Dec
2007
14 Dec
'07
8:30 p.m.
From: mcguire at neurotica.com
On Dec 14, 2007, at 7:09 AM, Allison wrote:
Hi
I have a parallel keyboard that runs from a 8035 ( romless 8048 ).
It has a clever way of generating the parallel output that would require
little circuit modification. He'd either have to get a 8035 and EPROM or
a 8748 as you suggested.
What they do is run the wires for the keyboard data as the same
signal lines as used to strobe the keyboard. While scanning the keyboard,
there is junk on the parallel output. Once a key is struck, it outputs
the ascii from a table, along with the parallel strobe.
This is a clever way to do two different things with the same I/O
pins.
The Keyboard I got was missing a few key codes that I needed for
my computer. Luckily, the ascii lookup tables were easy to spot in
a dump of the ROM. I just modified these and replaced the ROM with
an EPROM and my new tables.
Dwight
_________________________________________________________________
The best games are on Xbox 360. Click here for a special offer on an Xbox 360 Console.
http://www.xbox.com/en-US/hardware/wheretobuy/
I
recently bought a KayPro II keyboard. It contains a nice
Keytronics
mechanical keyboard and really nice case. I'd like to convert it
to a
parallel ASCII keyboard or just reuse its case but was wondering
if anyone
had the schematics?
Please let me know if you have the KapPro II keyboard schematics.
Thanks!
It has an 8048 uP if memory serves and the output is TTL level serial
ASCII. Making it put out parallel would be a major hackup including
reprogramming an 8748.