> 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.
Although not S100, the Intellec MCS8i was a 8080 machine with a front panel. There was no hardware way to start the processor at a particular address (No logic to jam a jump instruction onto the data bus, for example). You did have a reset switch. So what you did was take the bus over from the processor (thus effectively halting the latter), toggle a jump instruction with the appropriate address into the first 3 bytes of RAM, then reset, and give the bus back to the processor. That was even the way to start the ROM monitor program -tony
