This computer was one of the first "home" computers ever made, it was sold as a kit, but for additional money, you could buy one fully assembled.
It had no keyboard, the "program" had to be entered with the switches located on the front panel of the "computer", and as it didn't have video output (yet), the result was displayed via LEDs.
Another computer which had almost the same characteristics was launched by IMSAI and was called IMSAI 8080 (see both in the "Emulators" section).
The ALTAIR 8800 had one input port, also called the "Sense Switches" (I/O address 255) which was the left hand 8 address switches. Address 255 was also used on the IMSAI. The IMSAI front panel differed from the Altair in that you could also output to port 255 to a displayed LED buffer above the sense switches - a feature the Altair did not have (it only had input). The Altair sense switch were used during boot into Altair DOS to specify the terminal port to the DOS.
MITS made several peripherals and cards for this computer, namely, a video card, a serial card to connect a terminal, a RAM expansion card and a 8" floppy drive that used hard sectored floppies and stored 300 KB.
Several models were launched, they had the same characteristics except the CPU (8080 and later 8080A).
Believe it or not, the name "Altair" comes from Star Trek! The young daughter of the 'Popular Electronics' magazine editor gave it the name of the destination planet of the Enterprise from the episode she was watching.
Ha! The name Altair came from the great sci-fi movie of the 1950''s, ''''Forbidden Planet", starring Leslie Nielson. Evidently Mr. Roddenberry was a Forbidden Planet fan as well!
Monday 11th April 2011
Dave Brandt (US)
I had an early Altair bought as a kit from Dick Heiser''s computer store in Los Angeles, had it in my Winnebago motorhome with a LS 7700A terminal.
On a trip around the US in the motorhome, I bought a second dynamic 4K card from Bruce Seals (later to become Seals Electronics - another story) at his Knoxville, TN Byte Shop. The card didn''t work, stopped at MITS in NM on the way back to California, they showed me their repair facility and said that I could leave the card to be repaired if I wanted, said "no thanks" after seeing the 50 or 60 card pile awaiting repair.
I fixed the card myself, finding the refresh timimg was off, they used one-shots to time the refresh, with poor timing components. It took a dual trace scope and careful comparison against my working 4K card.
I used the Altair for many years, toggling in the bootstrap loader for the basic loaded from cassete tape.
Monday 5th January 2009
Pete Bickerdike (USA)
In 1975 When Bill Gates and Paul Allen Got their lates copy of Popular Electronics With The Story about the Altair 8800 they realised that this was what they were waiting for, they started a new company soon after called Micro-Soft