Brent Hilpert wrote:
One problem with a front panel on an S100 machine - or any
microprocessor-based machine - is getting access to the program
counter so you can tell it to start running at some arbitrary
address. The Altair/IMSAI panels resolved this with a hack, jamming a
jump instruction into the processor data lines (not the S100 bus data
lines) via a special connector to a special processor card.
In general, even if you can bus master to put stuff into memory,
front panel functionality is pretty limited if you don't have control
Regarding Cromemco, they did sell a blinkenlights
Z-1 which was essentially a Cromemco backplane
and cards in an IMSAI chassis.
Their ZPU processor card does have several option
jumpers to make it compatible with a front panel.