26 Jul
2006
26 Jul
'06
7:18 a.m.
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 :( 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.
I've got some old Volker Craig terminals with parallel keyboards on ribbon cables.
I'm know I've seen many others over the years ...
It would be
dead simple to make an adapter to convert a standard PC serial keyboard
into an ASCII/strobe parallel interface - you get the added benefits of having lots of
extra keys, and the ability to assign whatever codes you like to them.
I was pondering that. More than likely someone on this list has already done
exactly that. Speak now. ;-)
Somewhere around here I've got 8051 source
code to a little project I did to convert
a PC keyboard to an RS-232 serial interface - It would be very little work to turn that
into a parallel interface.
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)
I'm sure it'd be dead easy for someone who knows about programming PICs and
the like - as I say, I'm sure someone on here's done it even :-)