LED Output Register kit


In stock


David Hansel has designed several expansion cards for the new version 2.0 Altair-Duino kits. You can read more about those expansion cards on his Github page. Normally you are expected to have your own circuit boards produced and source your own parts. I have one of the simpler cards available in kit form.

One advantage of the IMSAI 8080 over the Altair 8800 was the output register at address 255 which would display the output value on a set of 8 LEDs on the front panel. This allowed for some crude but simple way of displaying data without needing any other devices. This simple card reproduces such a register for the Altair.

To output a value to the LEDs in BASIC just execute “OUT 255,x” where x is a byte value (0-255). The LEDs will display the binary representation of the given value.

Here is a simple BASIC program to flash the LEDs repeatedly in a random pattern:

10 X = INT(RND(1) * 255)
20 OUT 255, X
30 FOR I = 1 TO 100
50 GOTO 10

This kit includes everything you need to build the LED Output Register expansion card with all through-hole components. Simple assembly instructions are included.

This is included with the Altair-Duino Experimenter kit.