The Altair 8800 is a
microcomputer designed in 1974 by
MITS and based on the
Intel 8080
The Intel 8080 (''"eighty-eighty"'') is the second 8-bit microprocessor designed and manufactured by Intel. It first appeared in April 1974 and is an extended and enhanced variant of the earlier 8008 design, although without binary compatibil ...
CPU. Interest grew quickly after it was featured on the cover of the January 1975 issue of Popular Electronics and was sold by mail order through advertisements there, in ''
Radio-Electronics
''Radio-Electronics'' was an American electronics magazine that was published under various titles from 1929 to 2003. Hugo Gernsback, sometimes called the father of science fiction, started it as ''Radio-Craft'' in July 1929. The title was changed ...
'', and in other hobbyist magazines.
The Altair is widely recognized as the spark that ignited the
microcomputer revolution
The history of the personal computer as a mass-market consumer electronic device began with the microcomputer revolution of the 1970s. A personal computer is one intended for interactive individual use, as opposed to a mainframe computer where ...
as the first commercially successful personal computer. The
computer bus designed for the Altair was to become a
''de facto'' standard in the form of the
S-100 bus
The S-100 bus or Altair bus, IEEE 696-1983 ''(withdrawn)'', is an early computer bus designed in 1974 as a part of the Altair 8800. The bus was the first industry standard expansion bus for the microcomputer industry. computers, consisting of p ...
, and the first programming language for the machine was
Microsoft
Microsoft Corporation is an American multinational technology corporation producing computer software, consumer electronics, personal computers, and related services headquartered at the Microsoft Redmond campus located in Redmond, Washin ...
's founding product,
Altair BASIC
Altair BASIC is a discontinued interpreter for the BASIC programming language that ran on the MITS Altair 8800 and subsequent S-100 bus computers. It was Microsoft's first product (as Micro-Soft), distributed by MITS under a contract. Altair BASI ...
.
[ "This announcement ltair 8800ranks with IBM's announcement of the System/360 a decade earlier as one of the most significant in the history of computing."]
History
![MITS Rocket Light Flasher](https://upload.wikimedia.org/wikipedia/commons/d/db/MITS_Rocket_Light_Flasher.jpg)
While serving at the
Air Force
An air force – in the broadest sense – is the national military branch that primarily conducts aerial warfare. More specifically, it is the branch of a nation's armed services that is responsible for aerial warfare as distinct from an ...
Weapons Laboratory at
Kirtland Air Force Base,
Ed Roberts and
Forrest M. Mims III decided to use their electronics background to produce small kits for
model rocket
A model rocket are small rockets designed to reach low altitudes (e.g., for model) and be recovered by a variety of means.
According to the United States National Association of Rocketry (NAR) Safety Code, model rockets are constructed of ...
hobbyists. In 1969, Roberts and Mims, along with Stan Cagle and Robert Zaller, founded
Micro Instrumentation and Telemetry Systems
Micro Instrumentation and Telemetry Systems (MITS) was an American electronics company founded in Albuquerque, New Mexico that began manufacturing electronic calculators in 1971 and personal computers in 1975.
Ed Roberts and Forrest Mims foun ...
(MITS) in Roberts' garage in
Albuquerque, New Mexico, and started selling
radio
Radio is the technology of signaling and communicating using radio waves. Radio waves are electromagnetic waves of frequency between 30 hertz (Hz) and 300 gigahertz (GHz). They are generated by an electronic device called a transmi ...
transmitter
In electronics and telecommunications, a radio transmitter or just transmitter is an electronic device which produces radio waves with an antenna. The transmitter itself generates a radio frequency alternating current, which is applied to the ...
s and instruments for model rockets.
Calculators
The model rocket kits were a modest success and MITS wanted to try a kit that would appeal to more hobbyists. The November 1970 issue of ''Popular Electronics'' featured the Opticom, a kit from MITS that would send voice over an
LED light beam. As Mims and Cagle were losing interest in the kit business, Roberts bought his partners out, then began developing a calculator kit.
Electronic Arrays
Electronic Arrays, Inc. was a United States integrated circuit (IC) manufacturer of the 1960s and 70s. The company originated when Jim McMullen and other employees of General Microelectronics left to form McMullen Associates, which was later re ...
had just announced the EAS100, a set of six
large scale integrated (LSI) circuit chips that would make a four-function calculator.
The
MITS 816 calculator kit used the chipset and was featured on the November 1971 cover of ''Popular Electronics''. This calculator kit sold for , or $275 assembled.
Forrest Mims wrote the assembly manual for this kit and many others over the next several years. As payment for each manual he often accepted a copy of the kit.
The calculator was successful and was followed by several improved models. The MITS 1440 calculator was featured in the July 1973 issues of ''Radio-Electronics''. It had a 14-digit display, memory, and
square root
In mathematics, a square root of a number is a number such that ; in other words, a number whose ''square'' (the result of multiplying the number by itself, or ⋅ ) is . For example, 4 and −4 are square roots of 16, because .
...
function. The kit sold for and the assembled version was .
[ The cover story is for the MITS 1700 waveform generator. An ad for the MITS 1200, a battery operated handheld calculator, is on page 15.] MITS later developed a programmer unit that would connect to the 816 or 1440 calculator and allow programs of up to 256 steps.
Test equipment
In addition to calculators, MITS made a line of test equipment kits. These included an IC tester, a waveform generator, a digital voltmeter, and several other instruments. To keep up with the demand, MITS moved into a larger building at 6328 Linn NE in Albuquerque in 1973. They installed a
wave soldering
Wave soldering is a bulk soldering process used for the manufacturing of printed circuit boards. The circuit board is passed over a pan of molten solder in which a pump produces an upwelling of solder that looks like a standing wave. As the ci ...
machine and an assembly line at the new location. In 1972,
Texas Instruments
Texas Instruments Incorporated (TI) is an American technology company headquartered in Dallas, Texas, that designs and manufactures semiconductors and various integrated circuits, which it sells to electronics designers and manufacturers globa ...
developed its own calculator chip and started selling complete calculators at less than half the price of other commercial models. MITS and many other companies were devastated by this, and Roberts struggled to reduce his quarter-million-dollar debt.
''Popular Electronics''
In January 1972, ''Popular Electronics'' merged with another
Ziff-Davis
Ziff Davis, Inc. is an American digital media and internet company. First founded in 1927 by William Bernard Ziff Sr. and Bernard George Davis, the company primarily owns technology-oriented media websites, online shopping-related services, an ...
magazine, ''Electronics World''. The change in editorial staff upset many of their authors, and they started writing for a competing magazine, ''Radio-Electronics''. In 1972 and 1973, some of the best construction projects appeared in ''Radio-Electronics''.
In 1974, Art Salsberg became editor of ''Popular Electronics''. It was Salsberg's goal to reclaim the lead in electronics projects. He was impressed with
Don Lancaster
Donald E. Lancaster is an American author, inventor, and microcomputer pioneer.
Background
Lancaster is a writer and engineer, who authored multiple articles for computer and electronics magazines of the 1970s, including ''Popular Electronics' ...
's
TV Typewriter
The TV Typewriter is a video terminal that could display two pages of 16 lines of 32 upper case characters on a standard television set. The design, by Don Lancaster, appeared on the cover of '' Radio-Electronics'' magazine in September 1973.
Th ...
(''Radio Electronics'', September 1973) article and wanted computer projects for ''Popular Electronics''. Don Lancaster did an ASCII keyboard for ''Popular Electronics'' in April 1974. They were evaluating a computer trainer project by Jerry Ogden when the
Mark-8 8008
The Intel 8008 ("''eight-thousand-eight''" or "''eighty-oh-eight''") is an early byte-oriented microprocessor designed by Computer Terminal Corporation (CTC), implemented and manufactured by Intel, and introduced in April 1972. It is an 8-bit ...
-based computer by Jonathan Titus appeared on the July 1974 cover of ''Radio-Electronics''. The computer trainer was put on hold and the editors looked for a real computer system. (''Popular Electronics'' gave Jerry Ogden a column, ''Computer Bits'', starting in June 1975.)
[ "The breakthrough in low-cost microprocessors occurred just before Christmas 1974, when the January issue of Popular Electronics reached readers … "]
One of the editors, Les Solomon, knew MITS was working on an Intel 8080 based computer project and thought Roberts could provide the project for the always popular January issue. The TV Typewriter and the Mark-8 computer projects were just a detailed set of plans and a set of bare printed circuit boards. The hobbyist faced the daunting task of acquiring all of the integrated circuits and other components. The editors of ''Popular Electronics'' wanted a complete kit in a professional-looking enclosure.
Ed Roberts and his head engineer, Bill Yates, finished the first prototype in October 1974 and shipped it to ''Popular Electronics'' in New York via the
Railway Express Agency
Railway Express Agency (REA), founded as the American Railway Express Agency and later renamed the American Railway Express Inc., was a national package delivery service that operated in the United States from 1918 to 1975. REA arranged trans ...
. However, it never arrived due to a strike by the shipping company. Solomon already had a number of pictures of the machine and the article was based on them. Roberts got to work on building a replacement. The computer on the magazine cover is an empty box with just switches and LEDs on the front panel. The finished Altair computer had a completely different circuit board layout than the prototype shown in the magazine.
The January 1975 issues appeared on newsstands a week before Christmas of 1974 and the kit was officially (if not yet practically) available for sale.
The name
![Altair 8800 and Model 33 ASR Teletype](https://upload.wikimedia.org/wikipedia/commons/d/d7/Altair_8800_and_Model_33_ASR_Teletype_.jpg)
The typical MITS product had a generic name like the "
Model 1440 Calculator" or the "
Model 1600 Digital Voltmeter". Ed Roberts was busy finishing the design and left the naming of the computer to the editors of ''Popular Electronics''.
One explanation of the Altair name, which editor Les Solomon later told the audience at the first Altair Computer Convention (March 1976), is that the name was inspired by Les's 12-year-old daughter, Lauren. "She said why don't you call it Altair – that's where the Enterprise is going tonight."
["Les Solomon entertained a curious audience with anecdotes about how it all began for MITS, The name for MITS' computer, for example, was inspired by his 12-year-old daughter. She said why don't you call it Altair -- that's where the ''Enterprise'' is going tonight."] The ''
Star Trek'' episode is probably "
Amok Time
"Amok Time" is the second season premiere episode of the American science fiction television series '' Star Trek''. Written by science fiction author Theodore Sturgeon, scored by Gerald Fried, and directed by Joseph Pevney, it first aired o ...
", as this is the only one from ''The Original Series'' which takes the Enterprise crew to Altair (Six).
Another explanation is that the Altair was originally going to be named the PE-8 (Popular Electronics 8-bit), but Les Solomon thought this name to be rather dull, so Les, Alexander Burawa (associate editor), and John McVeigh (technical editor) decided that: "It's a stellar event, so let's name it after a star." McVeigh suggested "
Altair
Altair is the brightest star in the constellation of Aquila and the twelfth-brightest star in the night sky. It has the Bayer designation Alpha Aquilae, which is Latinised from α Aquilae and abbreviated Alpha Aql ...
", the twelfth brightest star in the sky.
[ Salsberg states that the Altair was named by John McVeigh]
Intel 8080
Ed Roberts had designed and manufactured programmable calculators and was familiar with the microprocessors available in 1974. He thought the
Intel 4004
The Intel 4004 is a 4-bit central processing unit (CPU) released by Intel Corporation in 1971. Sold for US$60, it was the first commercially produced microprocessor, and the first in a long line of Intel CPUs.
The 4004 was the first significa ...
and
Intel 8008
The Intel 8008 ("''eight-thousand-eight''" or "''eighty-oh-eight''") is an early byte-oriented microprocessor designed by Computer Terminal Corporation (CTC), implemented and manufactured by Intel, and introduced in April 1972. It is an 8-bit CP ...
were not powerful enough (in fact several microcomputers based on Intel chips were already on the market: the Canadian company
Microsystems International
Microsystems International Limited (MIL) was a telecommunications microelectronics company based in Ottawa, Ontario, Canada, founded in 1969. MIL was an early attempt to create a merchant semiconductor house by Nortel Networks (then Northern Elect ...
's CPS-1 built-in 1972 used a MIL MF7114 chip modeled on the 4004, the
Micral
Micral is a series of microcomputers produced by the French company Réalisation d'Études Électroniques ( R2E), beginning with the Micral N in early 1973. The Micral N was the first commercially available microprocessor-based computer.
In 1986, ...
marketed in January 1973 by the French company
R2E and the
MCM/70 marketed in 1974 by the Canadian company Micro Computer Machines); the National Semiconductor IMP-8 and
IMP-16
The IMP-16, by National Semiconductor, was the first multi-chip 16-bit microprocessor, released in 1973. It consisted of five PMOS integrated circuits: four identical RALU chips, short for register and ALU, providing the data path, and one CROM ...
required external hardware; the
Motorola 6800
The 6800 ("''sixty-eight hundred''") is an 8-bit microprocessor designed and first manufactured by Motorola in 1974. The MC6800 microprocessor was part of the M6800 Microcomputer System (latter dubbed ''68xx'') that also included serial and para ...
was still in development. So he chose the 8-bit
Intel 8080
The Intel 8080 (''"eighty-eighty"'') is the second 8-bit microprocessor designed and manufactured by Intel. It first appeared in April 1974 and is an extended and enhanced variant of the earlier 8008 design, although without binary compatibil ...
.
[ Wayne Green visited MITS in August 1975 and interviewed Ed Roberts. The article has several paragraphs on the design of the Altair 8800.] At that time, Intel's main business was selling memory chips by the thousands to computer companies. They had no experience in selling small quantities of microprocessors. When the 8080 was introduced in April 1974, Intel set the single unit price at (About in 2014 dollars). "That figure had a nice ring to it," recalled Intel's Dave House in 1984. "Besides, it was a computer, and they usually cost thousands of dollars, so we felt it was a reasonable price." Ed Roberts had experience in buying
OEM
An original equipment manufacturer (OEM) is generally perceived as a company that produces non-aftermarket parts and equipment that may be marketed by another manufacturer. It is a common industry term recognized and used by many professional or ...
quantities of calculator chips and he was able to negotiate a price (about in 2014 dollars) for the 8080 microprocessor chips.
Intel made the
Intellec-8 Microprocessor Development System that typically sold for a very profitable . It was functionally similar to the Altair 8800 but it was a commercial grade system with a wide selection of peripherals and development software.
[ "Intel Corporation has announced that an interactive display console and highspeed line printer are now available for the Intellec MDS microcomputer development system. … The display console costs and the printer in quantities of 1 to 9. Delivery is in 30 days. Price of the basic Intellec MDS with 16K bytes of RAM memory, including interfaces and resident software for operating the peripherals, is ."] Customers would ask Intel why their Intellec-8 was so expensive when that Altair was only . Some salesmen said that MITS was getting cosmetic rejects or otherwise inferior chips. In July 1975, Intel sent a letter to its sales force stating that the MITS Altair 8800 computer used standard Intel 8080 parts. The sales force should sell the Intellec system based on its merits and that no one should make derogatory comments about valued customers like MITS. The letter was reprinted in the August 1975 issue of MITS Computer Notes.
[ Intel letter to its sales force. "We wish to clarify any misconception that may exist in your minds regarding the MITS ALTAIR system. This product is designed around the Intel Standard Data Sheet 8080 family."] The "cosmetic defect" rumor has appeared in many accounts over the years although both MITS and Intel issued written denials in 1975.
[ "Ed Roberts was able to get around this problem by obtaining a supply of cosmetic reject chips for about 1/3 the retail price."]
The launch
![Altair Computer Ad May 1975](https://upload.wikimedia.org/wikipedia/commons/2/2e/Altair_Computer_Ad_May_1975.jpg)
For a decade, colleges had required science and engineering majors to take a course in computer programming, typically using the
FORTRAN or
BASIC languages.
[ Describes the introductory computer science courses at the University of Waterloo.] This meant there was a sizable customer base who knew about computers. In 1970, electronic calculators were not seen outside of a laboratory, but by 1974 they were a common household item. Calculators and video games like ''
Pong
''Pong'' is a table tennis–themed twitch arcade sports video game, featuring simple two-dimensional graphics, manufactured by Atari and originally released in 1972. It was one of the earliest arcade video games; it was created by Allan Al ...
'' introduced computer power to the general public. Electronics hobbyists were moving on to digital projects such as digital voltmeters and frequency counters. The Altair had enough power to be actually useful, and was designed as an expandable system that opened it up to all sorts of applications.
Ed Roberts optimistically told his banker that he could sell 800 computers, while in reality they needed to sell 200 over the next year just to break even. When readers got the January issue of ''Popular Electronics'', MITS was flooded with inquiries and orders. They had to hire extra people just to answer the phones. In February MITS received 1,000 orders for the Altair 8800. The quoted delivery time was 60 days but it was months before they could meet that. Roberts focused on delivering the computer; all of the options would wait until they could keep pace with the orders. MITS claimed to have delivered 2,500 Altair 8800s by the end of May.
[ "There was a subsequent article in February's Popular Electronics and the MITS people knew the Altair was here to stay. During that month alone, over 1,000 mainframes were sold. Datamation, March 1975." "By the end of May, MITS had shipped over 2,500 Altair 8800's"] The number was over 5,000 by August 1975. MITS had under 20 employees in January but had grown to 90 by October 1975.
[ "We had less than 20 employees when we introduced the Altair and now we have grown to 90 as a result of our Altair customers." Roberts also discussed the problems with the 4K dynamic RAM boards. Customers got a $50 refund.]
The Altair 8800 computer was a break-even sale for MITS. They needed to sell additional memory boards, I/O boards and other options to make a profit. The system came with a "1024 word" (1024 byte) memory board populated with 256 bytes. The BASIC language was announced in July 1975 and it required one or two 4096 word memory boards and an interface board.
MITS Price List, ''Popular Electronics'', August 1975.
*4K BASIC language (when purchased with Altair, 4096 words of memory and interface board) $60
*8K BASIC language (when purchased with Altair, two 4096-word memory boards and interface board) $75
MITS had no competition in the US for the first half of 1975. Their 4K memory board used dynamic RAM and it had several design problems.
The delay in shipping optional boards and the problems with the 4K memory board created an opportunity for outside suppliers.
An enterprising Altair owner, Robert Marsh, designed a 4K static memory that was plug-in compatible with the Altair 8800 and sold for $255.
His company was
Processor Technology
Processor Technology Corporation was a personal computer company founded in April 1975 by Gary Ingram and Bob Marsh in Berkeley, California. Their first product was a 4K byte RAM board that was compatible with the MITS Altair 8800 computer but mo ...
, one of the most successful Altair compatible board suppliers. Their advertisement in the July 1975 issue of ''Popular Electronics'' promised interface and PROM boards in addition to the 4K memory board. They would later develop a popular video display board that would plug directly into the Altair.
A consulting company in San Leandro, California,
IMS Associates, Inc., wanted to purchase several Altair computers, but the long delivery time convinced them that they should build their own computers. In the October 1975 issue of ''Popular Electronics'', a small advertisement announced the
IMSAI 8080
The IMSAI 8080 was an early microcomputer released in late 1975, based on the Intel 8080 and later 8085 and S-100 bus. It was a clone of its main competitor, the earlier MITS Altair 8800. The IMSAI is largely regarded as the first "clone" mi ...
computer. The ad noted that all boards were "
plug compatible
Plug compatible refers to " hardware that is designed to perform exactly like another vendor's product." The term PCM was originally applied to manufacturers who made replacements for IBM peripherals. Later this term was used to refer to IBM-co ...
" with the Altair 8800. The computer cost $439 as a kit. The first 50 IMSAI computers shipped in December 1975.
[ "Later that day, December 16 ]975
Year 975 ( CMLXXV) was a common year starting on Friday (link will display the full calendar) of the Julian calendar.
Events
By place
Byzantine Empire
* Arab–Byzantine War: Emperor John I raids Mesopotamia and invades Syria, using ...
United Parcel Service picked up the first shipment of 50 IMS computer kits for delivery to customers." The IMSAI 8080 computer improved on the original Altair design in several areas. It was easier to assemble: The Altair required 60 wire connections between the front panel and the motherboard (
backplane
A backplane (or "backplane system") is a group of electrical connectors in parallel with each other, so that each pin of each connector is linked to the same relative pin of all the other connectors, forming a computer bus. It is used as a back ...
.) The IMSAI motherboard had 18 slots. The MITS motherboard consisted of 4 slots segments that had to be connected together with 100 wires. The IMSAI also had a larger power supply to handle the increasing number of expansion boards used in typical systems. The IMSAI advantage was short lived because MITS had recognized these shortcomings and developed the Altair 8800B, which was introduced in June 1976.
In 1977,
Pertec Computer Corporation
Pertec Computer Corporation (PCC), formerly Peripheral Equipment Corporation (PEC), was a computer company based in Chatsworth, California which originally designed and manufactured peripherals such as floppy drives, tape drives, instrumentation c ...
purchased MITS and began to market the computer, without changes (except for branding), as the PCC 8800 in 1978.
Description
![Altair 8800b Computer](https://upload.wikimedia.org/wikipedia/commons/d/d1/Altair_8800b_Computer.jpg)
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 were not available, or would not 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
A backplane (or "backplane system") is a group of electrical connectors in parallel with each other, so that each pin of each connector is linked to the same relative pin of all the other connectors, forming a computer bus. It is used as a back ...
. 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 connector
An edge connector is the portion of a printed circuit board (PCB) consisting of traces leading to the edge of the board that are intended to plug into a matching socket. The edge connector is a money-saving device because it only requires a sin ...
s. The
S-100 bus
The S-100 bus or Altair bus, IEEE 696-1983 ''(withdrawn)'', is an early computer bus designed in 1974 as a part of the Altair 8800. The bus was the first industry standard expansion bus for the microcomputer industry. computers, consisting of p ...
was eventually acknowledged by the professional computer community and adopted as the
IEEE-696 computer bus standard.
The
Altair bus consists of the pins of the
Intel 8080
The Intel 8080 (''"eighty-eighty"'') is the second 8-bit microprocessor designed and manufactured by Intel. It first appeared in April 1974 and is an extended and enhanced variant of the earlier 8008 design, although without binary compatibil ...
run out onto the backplane. No particular level of thought went into the design, which led to disasters such as
shorting
In finance, being short in an asset means investing in such a way that the investor will profit if the value of the asset falls. This is the opposite of a more conventional " long" position, where the investor will profit if the value of t ...
from various power lines of differing
voltage
Voltage, also known as electric pressure, electric tension, or (electric) potential difference, is the difference in electric potential between two points. In a static electric field, it corresponds to the work needed per unit of charge to ...
s being located next to each other. Another oddity was that the system included two unidirectional
8-bit data buses, when the normal practice was for a single bidirectional bus (this oddity did, however, allow a later expansion of the S-100 standard to 16 bits bidirectional by using both 8-bit buses in parallel). A deal on power supplies led to the use of +8
V and +18V, which had to be locally regulated on the cards to
TTL
TTL may refer to:
Photography
* Through-the-lens metering, a camera feature
* Zenit TTL, an SLR film camera named for its TTL metering capability
Technology
* Time to live, a computer data lifespan-limiting mechanism
* Transistor–transistor lo ...
(+5V) or
RS-232
In telecommunications, RS-232 or Recommended Standard 232 is a standard originally introduced in 1960 for serial communication transmission of data. It formally defines signals connecting between a ''DTE'' (''data terminal equipment'') such ...
(+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
front panel
A front panel was used on early electronic computers to display and allow the alteration of the state of the machine's internal registers and memory. The front panel usually consisted of arrays of indicator lamps, digit and symbol displays, t ...
, which was inspired by the
Data General Nova
The Data General Nova is a series of 16-bit minicomputers released by the American company Data General. The Nova family was very popular in the 1970s and ultimately sold tens of thousands of units.
The first model, known simply as "Nova", was ...
minicomputer, included a large number of
toggle switch
In electrical engineering, a switch is an electrical component that can disconnect or connect the conducting path in an electrical circuit, interrupting the electric current or diverting it from one conductor to another. The most common type of ...
es to feed
binary
Binary may refer to:
Science and technology Mathematics
* Binary number, a representation of numbers using only two digits (0 and 1)
* Binary function, a function that takes two arguments
* Binary operation, a mathematical operation that ta ...
data directly into the memory of the machine, and a number of red
LEDs to read those values back out.
[ Ed Roberts said: "We had a Nova 2 by Data General in the office that we sold timeshare on …The front panel on an Altair essentially models every switch that was on the Nova 2. We had that machine to look at. The switches are pretty much standard of any front panel machine. It would have taken forever if we would have had to re-decide where every switch had to go. "]
Programming the Altair via the front panel could be a tedious and time-consuming process. Programming required the toggling of the switches to positions corresponding to the desired 8080 microprocessor instruction or
opcode in binary, then used the 'DEPOSIT NEXT' switch to load that instruction into the next address of the machine's memory. This step was repeated until all the opcodes of a presumably complete and correct program were in place. The only output from the programs was the patterns of lights on the panel. Nevertheless, many were sold in this form. Development was already underway on additional cards, including a
paper tape reader for storage, additional
RAM
Ram, ram, or RAM may refer to:
Animals
* A male sheep
* Ram cichlid, a freshwater tropical fish
People
* Ram (given name)
* Ram (surname)
* Ram (director) (Ramsubramaniam), an Indian Tamil film director
* RAM (musician) (born 1974), Dutch
* ...
cards, and an
RS-232
In telecommunications, RS-232 or Recommended Standard 232 is a standard originally introduced in 1960 for serial communication transmission of data. It formally defines signals connecting between a ''DTE'' (''data terminal equipment'') such ...
interface to connect to a proper Teletype
terminal
Terminal may refer to:
Computing Hardware
* Terminal (electronics), a device for joining electrical circuits together
* Terminal (telecommunication), a device communicating over a line
* Computer terminal, a set of primary input and output dev ...
.
Software
Altair BASIC
Ed Roberts received a letter from
Traf-O-Data
Traf-O-Data was a business partnership between Bill Gates, Paul Allen and Paul Gilbert that existed in the 1970s. The objective was to read the raw data from roadway traffic counters and create reports for traffic engineers. The company had only ...
asking if he would be interested in buying what would eventually be the
BASIC programming language
A programming language is a system of notation for writing computer programs. Most programming languages are text-based formal languages, but they may also be graphical. They are a kind of computer language.
The description of a programming ...
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
William Henry Gates III (born October 28, 1955) is an American business magnate and philanthropist. He is a co-founder of Microsoft, along with his late childhood friend Paul Allen. During his career at Microsoft, Gates held the positions ...
and
Paul Allen
Paul Gardner Allen (January 21, 1953 – October 15, 2018) was an American business magnate, computer programmer, researcher, investor, and philanthropist. He co-founded Microsoft Corporation with childhood friend Bill Gates in 1975, which ...
from the
Boston
Boston (), officially the City of Boston, is the state capital and most populous city of the Commonwealth of Massachusetts, as well as the cultural and financial center of the New England region of the United States. It is the 24th- mo ...
area, and they had no BASIC yet 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
A simulation is the imitation of the operation of a real-world process or system over time. Simulations require the use of models; the model represents the key characteristics or behaviors of the selected system or process, whereas the s ...
for the 8080 on a
PDP-10
Digital Equipment Corporation (DEC)'s PDP-10, later marketed as the DECsystem-10, is a mainframe computer family manufactured beginning in 1966 and discontinued in 1983. 1970s models and beyond were marketed under the DECsystem-10 name, espec ...
mainframe computer. 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
Altair BASIC is a discontinued interpreter for the BASIC programming language that ran on the MITS Altair 8800 and subsequent S-100 bus computers. It was Microsoft's first product (as Micro-Soft), distributed by MITS under a contract. Altair BASI ...
(aka MITS 4K BASIC), on a
paper tape. The first time it was run, it displayed "READY"
then Allen typed "PRINT 2+2" and it immediately printed the correct answer: "4". The game ''
Lunar Lander'' was entered in and this worked as well. Gates soon joined Allen and formed
Microsoft
Microsoft Corporation is an American multinational technology corporation producing computer software, consumer electronics, personal computers, and related services headquartered at the Microsoft Redmond campus located in Redmond, Washin ...
, then spelled "Micro-Soft".
Altair DOS
Announced in late 1975, it started shipping in August 1977.
See also
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SIMH
SIMH is a free and open source, multi-platform multi-system emulator. It is maintained by Bob Supnik, a former DEC engineer and DEC vice president, and has been in development in one form or another since the 1960s.
History
SIMH was based on ...
emulates Altair 8800 with both 8080 and
Z80
The Z80 is an 8-bit microprocessor introduced by Zilog as the startup company's first product. The Z80 was conceived by Federico Faggin in late 1974 and developed by him and his 11 employees starting in early 1975. The first working samples were ...
.
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IMSAI 8080
The IMSAI 8080 was an early microcomputer released in late 1975, based on the Intel 8080 and later 8085 and S-100 bus. It was a clone of its main competitor, the earlier MITS Altair 8800. The IMSAI is largely regarded as the first "clone" mi ...
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References
Further reading
Books
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* Chapter 6 "Mechanics: Kits & Microcomputers"
Magazines
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External links
* {{cite web, title=Altair 8800 , publisher=New Mexico Museum of Natural History and Science , url=http://startup.nmnaturalhistory.org/gallery/item.php?ii=26 , access-date=2007-12-18 , url-status=dead , archive-url=https://web.archive.org/web/20120323162008/http://startup.nmnaturalhistory.org/gallery/item.php?ii=26 , archive-date=March 23, 2012
MITS Altair 8800 exhibit at old-computers.com's virtual computer museumVirtual Altair MuseumAltair 8800 images and information at vintage-computer.comMaker of a hardware emulation of the 8800 running on an Atmel AVR 8515Altair 8800 CloneTrue-to-life MITS Altair 8800 online simulator
Early microcomputers
Computer-related introductions in 1974
S-100 machines
8-bit computers