ALTAIR 8800 micro Users Manual
© Briel Computers 2010 page 9
Chapter 1: Introducing the Altair 8800 micro
The Altair 8800 micro is the result of 5 years of concept ideas and many failures. While the project spent much
time on the shelf, the desired result would keep this project alive. The micro is based on a simple early version
Altair 8800 with memory and a serial card for I/O. The project goal was to design a system that could be
programmed like the original with toggle switches and could run the original Altair BASIC programming
language. The micro is the first in a series of Altair clones that will be released. A full size version will be in the
works after the initial release of the micro that will be a front panel only and then the original concept AltairPC.
Final Altair 8800 micro prototype
You may have noticed that not all of the original Altair I/O status LED’s are on the front panel. This is due to
the limited amount of I/O and the limited amount of physical space allotted on the front panel itself. The
missing LED’s are INTE, PROT, WAIT, and HLDA. In addition to the missing LED’s one AUX switch was
also not included on the board. The AUX switches were not directly used on the original Altair but the one
AUX switch on the Altair micro serves as a boot loader and memory storage detector.
Choosing a processor was no easy choice. Most replica computers created by Briel Computers use authentic
processors that are identical to those used in the original systems. The Altair 8800 micro is different. The
original processor (i8080) has multiple voltage requirements making design implementation difficult for kit
purposes at a low price. The Z80 processor is very close to the 8080 and most code works with it. The problem
is that it doesn’t run Altair BASIC and was one of the failed concepts. This processor failure set the project
back over 2 years. After considering using the 8085 (software compatible), I opted to emulate the CPU in a
microcontroller. The main reason was chip reduction. With a microcontroller I am able to not only embed an
emulated version of the 8080; I can also emulate most of the Altair system in 1 chip. The main CPU
microcontroller has the nickname AOAC (Altair on a chip). While there are I/O pin limitations, a handful of
latches can give you as much I/O as you need.
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