MITS Altair 8800a

Description
Manufacturer	Micro Instrumentation and Telemetry Systems (MITS)
Model	Altair 8800a
Date Announced	Late 1975 or early 1976
Date Canceled	1977 or 1978
Number Produced	Unknown
Country of Origin	USA
Price	Approximately $550 in kit form, Approximately $800 assembled for the basic system.
Current Value	$1,000 - $2,500

Specifications	---
Processor	Intel 8080a
Speed	2 MHz
RAM	1K to 64K
ROM	Optional. Usually Intel 1702 EPROMs at 256 Bytes each for various bootstrap loaders.
Storage
Expansion	18 slot motherboard. Typically not fully populated with connectors.
Bus	S-100
Video
I/O	Optional Serial and Paralell
OS Options	MITS DOS, CP/M, Altair Disk BASIC

Notes	The Altair 8800a was a slight upgrade to the 8800 that was introduced alongside the Altair 8800B. The main change was an upgraded power supply although the new 18 slot motherboard was also significant. Early 8800a models had the short round switches like the 8800, some later models seem to have had the 8800b flat switches instead.

Related Items in Collection	Altair 8" Disk drives with controller cards, ADM-3A terminal, ASR 33 teletype, various software including Altair Disk BASIC, Altair DOS, Fortran, Timeshare BASIC, etc. Manuals for all hardware and software.
Related Items Wanted	Additional software and working disk drives. Interrupt controller, PROM programmer, PROM board.

I documented the MITS Altair 8800a I received in a similar manner to the MITS Altair 8800.

Out of the box, the Altair 8800a looked pretty good. There was some case damage, but the front panel was nearly perfect.

The inside of the MITS Altair 8800a as delivered

The insides of this machine, much like the 8800, were dirty and rusty, but operable.

The Rev 1 CPU card is in fairly good shape. An Intel 8080A drives the machine.

The first of two Altair Disk boards for the 8800a

Like my 8800, this machine has a 2 card disk subsystem. It's a different version then the one in the other machine, which can be seen on these two cards.

The second of two Altair Disk boards for the 8800a

This disk controller card is most significantly different from its sibling in the other Altair machine.

The MITS Altair 8800a EPROM card which is actually a Solid State Music card

The 8800a EPROM card has two EPROMs mounted. One is the general boot loader (tape and paper tape) while the other is the boot loader for the disk drive. I'm not yet sure if there is still data on the EPROMs.

One of the two 88-SIO-2 cards in the MITS Altair 8800a

This machine hosted a multi-user system and probably had several terminals attached at one time. There were 2 SIO-2 serial cards installed.

The MITS 16k static RAM card from the MITS Altair 8800a

This machine had 56K of RAM installed. 24K static and 32K dynamic. This is the 16K static card.

One of the two 16k dynamic RAM cards from the MITS Altair 8800a

There are two of these 16K dynamic RAM cards in this Altair. I'm not sure how well Static and Dynamic RAM get along in the same system. I'll find out in time, I'm sure.

The two disk drives (88-DCDD) that came with the Altairs

Here are the two Altair disk drives. The one without the label (and without a power switch) belongs to this machine.

MITS Altair Documentation including assembly and operations manuals, MITS Disk Extended BASIC manuals and manuals for the 8 inch disk drives

The original owner of the Altairs in my collection came across some additional documentation after a move. Included were the manuals for the disk drives, the 8800a and almost all of the S-100 cards supplied with the machines!