25 Nov
1998
25 Nov
'98
1:36 p.m.
Not trying to be a snob here, but true "Front Panel Theory" can only be
practiced on a computer where the 'innards' are exposed. Most
microprocessors are too integrated to support a "real" front panel. This is
one of the reason they died out fairly quickly in the micro world but lived
for quite a while in the mini-world.
Basically an ideal front panel contains enough switches to set any memory
address, load any register, and start, stop, and single step the CPU, and
enough lights to monitor both system state and the current address. Many
older panels let you look at several things simultaneously but later ones
like the PDP-11 and PDP-8 panels used selector switches to multiplex the
lights and reduce cost.
--Chuck
At 06:03 PM 11/25/98 -0600, you wrote:
This might be a bit of an odd question, but can anyone
point me in the
right direction to find info on theory of operation of a front panel? I
have a z80 based computer which I built a few years ago (wire-wrapped)
which uses an eprom for program storage. I would like to add a front
panel (switches and lights) to it to get better aquainted with the old way
of doing things. Unfortunatly, my knowledge of microprocessor-based
systems post-dates the era of front panels. The eventual goal is to build
a hands-on display to show how systems were bootstrapped. (without
letting people abuse a 'priceless' altair or imsai)
Thanks,
srw