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.