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Altair 8800c Front Panel Board Set
Ver 1.2, Feb 2019
Introduction
The Altair 8800c front panel
board set is a drop-in re-
placement for the original Al-
tair 8800 front panel board.
The new board set was creat-
ed for the following reasons:
1) Availability
Finding an original front panel board to restore
or build an Altair is nearly impossible. The new
board set provides a drop-in equivalent that is
readily available.
2) Elimination of the Hand-Wired Harness
The original front panel board picked up bus sig-
nals and connected to the CPU board through a
large hand-wired harness. This harness was te-
dious to build and was often a reliability issue –
especially if you had to remove and work on the
front panel board. The 8800c board set replaces
the hand-wired harness with a 50 pin ribbon ca-
ble that connects to a bus interface board (shown here) to pick up and drive the required bus signals.
3) Mechanical Compatibility with the Altair 8800 Clone Cabinet
The original Altair 8800 cabinet made by Optima is no longer manufactured, and like the original
front panel board, finding an original cabinet by itself is nearly impossible. As an alternative, the cab-
inet for the Altair 8800 Clone is still available, however, the original front panel board covers mount-
ing points in the Clone cabinet’s front panel bracket. This new front panel board is designed to fit
properly in the Clone cabinet’s mounting bracket. The new front panel board also fits in an original
Altair cabinet.
4) Compatible with the 8800b CPU Board
The original front panel board does not work with an Altair 8800b CPU board and vice-versa. This is
due to a change in how the 8800b front panel injects data into the CPU and how it stops the CPU. For
increased flexibility, the new front panel set works with both the original and the 8800b CPU boards.
5) Logic Error Fixes
The original front panel board had a few logic problems that are fixed in the new front panel board
set. These same problems were also fixed by MITS when they designed the 8800b computer.
CPU “Stop” Timing Error
The Stop switch is designed to put the 8080 into a wait state on an instruction fetch bounda-
ry (the M1 cycle). However, due to a timing issue in the run/stop circuit, the front panel
doesn’t always stop on an M1 cycle.
