Posted on 12/19/2006 8:14:07 AM PST by yankeedame
The MITS Altair 8800 was a microcomputer design from 1975, based on the Intel 8080A CPU. Sold as a kit through Popular Electronics magazine, the designers intended to sell only a few hundred to hobbyists, and were surprised when they sold over ten times that many in the first month.
Today the Altair is widely recognized as the spark that led to the personal computer revolution of the next few years: The computer bus designed for the Altair was to become a de facto standard in form of the S-100 bus, and the first programming language for the machine was Microsoft's founding product, Altair BASIC.
History While serving at the Air Force Weapons Laboratory at Kirtland Air Force base, New Mexico, Ed Roberts and Forrest M. Mims III decided to use their electronics background to produce small kits for model rocket hobbyists. Roberts and Mims, along with Stan Cagle and Robert Zaller, founded Micro Instrumentation and Telemetry Systems (MITS) in Roberts' garage in Albuquerque, New Mexico, and started selling radio transmitters and instruments for model rockets.
In 1969 Roberts bought out the others and moved to a larger office, where he manufactured calculator kits for hobbyists. Mims assisted by writing manuals for some of the products in return for kits. In 1972, Texas Instruments developed their own calculator chip and started selling complete calculators at more than half the going rate. MITS was devastated by this, as were many other companies, and Roberts struggled to reduce his quarter-million dollar debt.
With the release of the first 8-bit microprocessor, the Intel 8008, in 1972, and the more powerful 8080 in 1974, a number of hobbyists started designing microcomputer kits. In July 1974, one such design, Jonathan Titus' well thought-out Mark-8, based on the 8008, was advertised in Radio-Electronics magazine. The design was purely on paper, requiring the builder to track down the parts one at a time, a task that was basically impossible outside of California. Although the Mark-8 was not a success, the editors at Popular Electronics realized that someone was going to be the first to deliver a "real" kit, and decided they wanted to do it. At this point the story becomes somewhat less clear.
The design Roberts looked for a deal on CPUs, and eventually talked Intel into supplying him with cosmetically blemished 8080's for $75, when they normally sold for $360. In fact the deal wasn't quite as shrewd as Roberts thought at the time; Intel chose the $360 price simply as a play on the famous IBM System/360 mainframe. The name finally decided upon for the computer came from Solomon's 12-year-old daughter, Lauren. She suggested Altair, which was the destination for the Starship Enterprise during an episode of Star Trek that she was watching.
The first working sample was immediately shipped, by train, to New York. However, it never arrived due to a strike by the shipping company. The first example of this groundbreaking machine is thus lost to history. Solomon had already taken a number of pictures of the machine and wrote the article based on them, while Roberts got to work on building a replacement. Everything came together, and the kit was officially available on December 19, 1974.
The launch
Popular Electronics, January 1975The kit was first announced in the January 1975 edition of Popular Electronics. The timing seemed to be just right. The electronics hobbyists were moving on to computers as more and more electronics turned digital, and yet they were frustrated by the low power and flexibility of the few kits that were already on the market. The Altair had enough power to be actually useful, and was designed around an expandable system that opened it up to all sorts of experiments. Roberts needed to sell 200 over the next year to break even, but instead received thousands of orders in the first month, including 200 in one day.
Within only six months competition arrived in the form of the IMSAI 8080, which included a keyboard, monitor and a floppy disk controller. Roberts was furious, and spent an increasing amount of his time trying to "knock off" these competitors instead of improving the Altair. By 1976 there were a number of much better built machines on the market, and when Roberts started demanding the newly-appearing computer stores sell only Altair machines, they instead turned to the competition and, in a turn of irony, MITS was quickly squeezed out of the market they themselves had created.
Description In the first design of the Altair, the parts needed to make a complete machine would not fit on a single motherboard, and the machine consisted of four boards stacked on top of each other with stand-offs. Another problem facing Roberts was that the parts needed to make a truly useful computer weren't available, or wouldn't be designed in time for the January launch date.
So during the construction of the second model, he decided to build most of the machine on removable cards, reducing the motherboard to nothing more than an interconnect between the cards, a backplane. The basic machine consisted of five cards, including the CPU on one and memory on another. He then looked for a cheap source of connectors, and came across a supply of 100-pin edge connectors.
The rest, as they say, is history, and the S-100 bus was eventually acknowledged by the professional computer community and adopted as the IEEE-696 computer bus standard.
For all intents, the Altair bus consists of the pins of the Intel 8080 run out onto the backplane. No particular level of thought (or rushed design) went into the design, which led to such disasters as various power lines of differing voltages being located next to each other, leading to easy shorting. Another oddity was that the system included two unidirectional 8-bit data buses, but only a single bidirectional 16-bit address bus. A deal on power supplies led to the use of +8V and +18V, which had to be "pulled down" on the cards to TTL (+5V) or RS-232 (+12V) standard voltage levels.
The Altair shipped in a two-piece case. The backplane and power supply were mounted on a base plate, along with the front and rear of the box. The "lid" was shaped like a C, forming the top, left and right sides of the box. The face plate, reportedly inspired by the Data General Nova minicomputer, included a number of large toggle switches to feed binary data directly into the memory of the machine, and a number of red LEDs to read those values back out.
Programming the Altair was an extremely tedious process where one toggled the switches to positions corresponding to an 8080 opcode, then used a special switch to enter the code into the machine's memory, and then repeated this step until all the opcodes of a presumably complete and correct program was in place. When the machine first shipped the switches and lights were the only interface, and all one could do with the machine was make programs to make the lights blink. Nevertheless, many were sold in this form. Roberts was already hard at work on additional cards, including a paper tape reader for storage, additional RAM cards, and a RS-232 interface to connect to a proper terminal.
Software
Altair BASIC Main article: Altair BASIC Around this time Roberts received a letter from a Seattle company asking if he would be interested in selling their BASIC programming language for the machine. He called the company and reached a private home, where no one had heard of anything like BASIC. In fact the letter had been sent by Bill Gates and Paul Allen from the Boston area, and they had no BASIC to offer. When they called Roberts to follow up on the letter he expressed his interest, and the two started work on their BASIC interpreter using a self-made simulator for the 8080 on a PDP-10 minicomputer. They figured they had 30 days before someone else beat them to the punch, and once they had a version working on the simulator, Allen flew to Albuquerque to deliver the program, Altair BASIC (aka MITS 4K BASIC), on a paper tape. Miraculously it worked the first time, and Gates soon joined him and formed Microsoft, then spelled "Micro-Soft".
And I bought a TRS-80 just a few years later...
Trash 80 for me too
That brings back memories. How I wanted a CompuColor, and my pal Chip wanted an Exidy Sorcerer. Others had Apple IIs, Sol, Commodore PET, Atari 400, TI 99/4, Ohio Scientific and more. The arguments between the 6502ers and the 8080, 8080a and Z-80 poeple could go on forever. In some ways, the computers were more fun, then.
My first computer was a Timex Sinclair. I think I still have it up in the attic somewhere...
I was playing Arcade Classics on my Playstation 2 when I suddenly realized I was playing 8-bit games on a machine that is too powerful to export to some countries because it could be used to guide a nuke.
Real men program with toggle switches!
I always wanted a Commodore PET, but my first "computer" was a Texas Instruments SR-52. It was replaced with a TI-59 a few years later.
I have mine, too, safely packed away in my "Antique Electronics" box. ;)
How (or when) did the name change to Atari (or was that a take-off for the game player only)?
TRS was "Tandy Radio Shack" abbreviation, right?
On one date, three weeks earlier, November 30, 1950 -- 781 Americans gave their lives in the "police action" against "bandits" in Korea and Truman hinted that he might use the A-bomb.
In the Trash-80 Club.
I learned on a PDP-11.
Not too mini.
And two bit parity.
No. Just a wannabe. I quickly graduated to a Kapro II and then the amazing Kapro IV before jumping on the IBM bandwagon.
I started with a Sinclair, too. I went through all the models from the Sinclair ZX80 and ZX81, the Sinclair Spectrum, the Sinclair QL and finally the Sinclair laptop Z88. I still have all of them and I fire them up now and again.
Still alive with Uncle Clive.
Did you get the 8K memory module for the Sinclair? That brings you up to a screaming 16K of memory!
The UYK-7 had many toggle switches.
I am a computer engineer today because of the Imsai 8080 built by my brother-in-law. I started progammming on it and the rest is history.
You never forget your first.....computer.
sigh.
(how many people still have their first computer somewhere?)
Note the article on CCD's as well, tech convergence...
The first computer I dealt with filled an acre-and-a-half chilled room on Kadena AFB in 1969. The first one I owned was a Sinclair that attached to a TV.
I wanted one of those so bad, but as a poor student I couldn't afford it. It would be several years until I bought an Alspa ACI-2 CP/M system.
Doesn't look like a Krell machine to me. They were from Altair too.
LOL
I thought a PDP-11-73 with terminal *was* a home computer, it did not need a room sized AC unit to keep it cool.
Ah, the days of Big Iron are over....
thank goodness.
All I knew was that there was a big cold room backing up the terminals. I learned basic Basic on that dinosaur.
Availability:
The first 5 kits have been sold. All parts for 20 more units are on order. The cases are expected to arrive near the 18th of January, 2007. Kits can begin shipping by the 22nd. These kits are available for sale at $1499. Discounts for veterans and active military are available. Reservations for the next run of 20 units may be made now. I will not expect or accept any money until a kit is ready to be sold.Details:
The Altair 8800 Kit is built using the highest quality parts available. Every part is new or new old stock. Every part required to complete the kit is included except the power cord, which I do not want to include due to possible liability issues.The kit contains:
-Revision 0 Display/Control board, revision 0 CPU board, revision 0 1k SRAM board, and revision 0 motherboardThis Altair kit is functionally and in most ways physically identical to the original Altair 8800 Computer. A complete listing of differences will be available later this week at http://www.altairkit.com. If you have any questions, please feel free to contact me! I will be glad to provide requested pictures, specifications, or a description of your area of interest. Any peripheral or software designed for the Altair will work without a problem in this unit.
-Genuine Optima enclosure with powder coated and ink silk screened dress panel
-ALL parts required to complete the kit (please see "More Pictures" for examples of kit contents)
-8v 100W Switching Power Supply, +16v/-16v/5v 60W Switching Power Supply
-Restored Altair 8800 Construction Manual, Technical Manual, Operators Manual, as well as my own full color assembly guide with step-by-step instructions illustrating the assembly process. Over 80 hours has been put just into the documentation (deleting copy machine specks, positioning text blocks and page numbers, etc) The manual is printed on 28lb premium Hammermil paper and bound in a 1" D ring binder. (available for PDF download in the next few days)
Additional 4 slot motherboard kits (with 4 card edge connectors) are available at a price of $90 each.
The kit comes with a guarantee that you will end up with a fully functional Altair. As long as you make a good effort at assembling the kit, and pay shipping both ways, I will diagnose and repair your kit for free. This guarantee does not cover physical damage to any part during or because of incorrect installation. Some parts, if damaged, cost so little that I would not charge for replacement. PCBs, Power supply, or the case for example would not be replaced for free.
See "More Pictures for the kit contents!
And the best part was that in only 20 or so lines you could make it add numbers or say YES. Exciting.
Our newest had an 80 GB drive and I think that's too small already.
Ah yes, the Timex/Sinclair. Used a magnetic tape recorder to store programs, used the TV as a monitor. Sold for $50 with 1k of memory and you built it yourself. $50 more and they would throw in 10k more memory. $50 on top of that and they would build it for you.
Amazing how far we have come in just 25+ years!!!
If I recall correctly, there was a Heathkit type unit that came out right around this time too. I believe reading about it in Popular Electronics at the time. For a certain amount of dollars you could have it ready assembled, otherwise you just ordered the parts from them, and put it together yourself. However, the parts list, schematic and instructions were all in the article.
And to think that a mere three or four years later, I cut my programming teath on a top of the line Commodore Pet with cassette tape storage with a whole 32K of RAM. I wrote a program called Kingmaker, you had to plant corn, and buy cats to kill the rats that ate the corn (or your people would starve). I couldn't figure out why the stupid thing always had these quirky bugs. That's when I discovered the "bug" of FIFO program-sequence RAM stack "cliff" on that machine. When you filled RAM up with instructions, entering another line of code would cause the first instruction entered to be pushed off of the stack. If that was an important line of code (not a REM statement), wierd things would happen at execution time. Typing that line in again (e.g. loop initialization) would cause the next line of code entered to drop out off of the memory stack.
My first was an IBM 1620.
The first I built was a Southwest Technical Products MP-68.
'63 and '76 respectively.
I'm amazed at how much things changed between 1980 and 1990. It was a whole century computerwise played out in 10 years
I even got a 64k memory add-on and a printer, eventually. I still have the thing but I don't have a TV to attach it to or an inclination to fire it up.
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