On 7/27/06, Jules Richardson <julesrichardsonuk at yahoo.co.uk> wrote:
Dave Dunfield wrote:
Looking
for thoughts on which machines used parallel ASCII keyboards...
Many (perhaps most) older equipment with an integrated keyboard (ie: not
on a cable) used parallel keyboards - also any with an external keyboard on
a ribbon cable are likely parallel.
Hmm, most of the ones (internal keyboards) I've seen are dumb - the large
number of lines exiting the keyboard are just connected direct to the matrix
and the decoding is done by something on the main CPU board (often the CPU
itself), so not easily transferrable to another system :(
That was certainly the case for Commodore equipment (PET, VIC-20, C-64...)
Agreed on the external keyboards with a ribbon cable -
but I'm struggling to
think of that many systems which used them to be honest. Most micros had
integrated keyboards, whilst workstation-class stuff was often pretty
proprietary and usually serial. Machines laying somewhere inbetween often seem
to just use a serial port and rely on a separate terminal for their input.
My recollection is that the mid-1970s were the heyday of ASCII
keyboards (AIM-65 and similar machines). By the early 80s, small
machines tended to have matrix scanned (proprietary) raw keyboards or
some serial interface, as you mention, in both cases for cost.
Quite by chance I found such a thing this morning at:
http://www.beyondlogic.org/keyboard/keybrd.htm#1
... the HC705 IC (not a chip I'm familiar with) used may not have enough ports
though if port A needs to be used exclusively by the keyboard (due to high
impedance requirements) and port B is only 8 bits and tied up with the ASCII
interface (plus the strobe line to the machine needs to go somewhere)
Could that be a Motorola 68HC705?
-ethan