Altair BASIC
Encyclopedia
Altair BASIC was an 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 BASIC was the start of the Microsoft BASIC
product range.
recalls that when he and Paul Allen
read about the Altair in the January 1975 issue of Popular Electronics
, they understood that the price of computers would soon drop to the point that selling software for them would be a profit
able business. Gates believed that by providing a BASIC interpreter for the new computer they could make it more attractive to hobbyists. They contacted MITS founder Ed Roberts, told him that they were developing an interpreter, and asked whether he would like to see a demonstration. This followed the common engineering industry practice of a trial balloon
, an announcement of a non-existent product
to gauge interest. Roberts agreed to meet them for a demonstration in a few weeks, in March 1975.
Gates and Allen had neither an interpreter nor even an Altair system on which to develop and test one. However, Allen had written an Intel 8008
emulator
for their previous venture, Traf-O-Data
, that ran on a PDP-10
time-sharing
computer. He adapted this emulator based on the Altair programmer guide, and they developed and tested the interpreter on Harvard's PDP-10. Harvard officials were not pleased when they found out, but there was no written policy that covered the use of this computer. Gates and Allen bought computer time from a timesharing service in Boston to complete their BASIC. They hired Harvard student Monte Davidoff
to write floating-point arithmetic routines for the interpreter, a feature not available in many of its competitors.
The finished interpreter, including its own I/O
system and line editor
, fit in only four kilobytes of memory, leaving plenty of room for the interpreted program. In preparation for the demo, they stored the finished interpreter on a punched tape
that the Altair could read and Paul Allen flew to Albuquerque.
On final approach, Allen realized that they had forgotten to write a bootstrap program to read the tape into memory. Writing in 8080 machine language, Allen finished the program before the plane landed. Only when they loaded the program onto an Altair and saw a prompt asking for the system's memory size did Gates and Allen know that their interpreter worked on the Altair hardware. Later, they made a bet on who could write the shortest bootstrap program. Gates won.
Roberts agreed to distribute the interpreter. He also hired Gates and Allen to maintain and improve it, causing Gates to take a leave of absence from Harvard. They produced several versions: the original 4K BASIC and later 8K BASIC, Extended Basic, Extended ROM BASIC, and Disk BASIC.
As they expected, the Altair was very popular with hobbyists such as the Homebrew Computer Club
. Altair BASIC, as MITS's preferred BASIC interpreter, was also popular. However, the hobbyists took a "share-alike" approach to software and thought nothing of copying the BASIC interpreter for other hobbyists. Homebrew member Dan Sokol was especially prolific; after somehow obtaining a pre-market tape of the interpreter, he made 25 copies and distributed them at the next Homebrew meeting, urging recipients to make more copies. Gates responded in 1976 with a strongly worded Open Letter to Hobbyists
that accused the copiers of theft
and declared that he could not continue developing computer software that people did not pay for. Many hobbyists reacted defensively to the letter.
Under the terms of the purchase agreement, MITS would receive the rights to the interpreter after it had paid a certain amount in royalties. However, Microsoft had developed versions of the interpreter for other systems such as the Motorola 6800
. When they decided to leave MITS, a dispute arose over whether the full amount had been paid and whether the agreement applied to the other versions. Microsoft and MITS took the dispute to an arbitrator, who much to Roberts' surprise decided in favor of Microsoft. BASIC interpreters remained the core of Microsoft's business until the early 1980s, when it shifted to MS-DOS
.
Interpreter (computing)
In computer science, an interpreter normally means a computer program that executes, i.e. performs, instructions written in a programming language...
for the BASIC programming language that ran on the MITS
Micro Instrumentation and Telemetry Systems
Micro Instrumentation and Telemetry Systems 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 founded MITS in December 1969 to produce miniaturized telemetry...
Altair 8800
Altair 8800
The MITS Altair 8800 was a microcomputer design from 1975 based on the Intel 8080 CPU and sold by mail order through advertisements in Popular Electronics, Radio-Electronics and other hobbyist magazines. The designers hoped to sell only a few hundred build-it-yourself kits to hobbyists, and were...
and subsequent S-100 bus
S-100 bus
The S-100 bus or Altair bus, IEEE696-1983 , was an early computer bus designed in 1974 as a part of the Altair 8800, generally considered today to be the first personal computer...
computers. It was Microsoft
Microsoft
Microsoft Corporation is an American public multinational corporation headquartered in Redmond, Washington, USA that develops, manufactures, licenses, and supports a wide range of products and services predominantly related to computing through its various product divisions...
's first product (as Micro-Soft), distributed by MITS under a contract. Altair BASIC was the start of the Microsoft BASIC
Microsoft BASIC
Microsoft BASIC was the foundation product of the Microsoft company. It first appeared in 1975 as Altair BASIC, which was the first BASIC, and the first high level programming language available for the MITS Altair 8800 hobbyist microcomputer....
product range.
Origin and development
Bill GatesBill Gates
William Henry "Bill" Gates III is an American business magnate, investor, philanthropist, and author. Gates is the former CEO and current chairman of Microsoft, the software company he founded with Paul Allen...
recalls that when he and Paul Allen
Paul Allen
Paul Gardner Allen is an American business magnate, investor, and philanthropist. Allen co-founded Microsoft with Bill Gates...
read about the Altair in the January 1975 issue of Popular Electronics
Popular Electronics
Popular Electronics was an American magazine started by Ziff-Davis Publishing in October 1954 for electronics hobbyists and experimenters. It soon became the "World's Largest-Selling Electronics Magazine". The circulation was 240,151 in April 1957 and 400,000 by 1963. Ziff-Davis published Popular...
, they understood that the price of computers would soon drop to the point that selling software for them would be a profit
Profit (accounting)
In accounting, profit can be considered to be the difference between the purchase price and the costs of bringing to market whatever it is that is accounted as an enterprise in terms of the component costs of delivered goods and/or services and any operating or other expenses.-Definition:There are...
able business. Gates believed that by providing a BASIC interpreter for the new computer they could make it more attractive to hobbyists. They contacted MITS founder Ed Roberts, told him that they were developing an interpreter, and asked whether he would like to see a demonstration. This followed the common engineering industry practice of a trial balloon
Trial balloon
A trial balloon is information sent out to the media in order to observe the reaction of an audience. It can be used by companies sending out press releases to judge reaction by customers, or it can be used by politicians who deliberately leak information on a policy change under consideration...
, an announcement of a non-existent product
Vaporware
Vaporware is a term in the computer industry that describes a product, typically computer hardware or software, that is announced to the general public but is never actually released nor officially canceled. Vaporware is also a term sometimes used to describe events that are announced or predicted,...
to gauge interest. Roberts agreed to meet them for a demonstration in a few weeks, in March 1975.
Gates and Allen had neither an interpreter nor even an Altair system on which to develop and test one. However, Allen had written an Intel 8008
Intel 8008
The Intel 8008 was an early byte-oriented microprocessor designed and manufactured by Intel and introduced in April 1972. It was an 8-bit CPU with an external 14-bit address bus that could address 16KB of memory...
emulator
Emulator
In computing, an emulator is hardware or software or both that duplicates the functions of a first computer system in a different second computer system, so that the behavior of the second system closely resembles the behavior of the first system...
for their previous venture, Traf-O-Data
Traf-O-Data
Traf-O-Data was a partnership between Bill Gates, Paul Allen, and Paul Gilbert. The objective was to read the raw data from roadway traffic counters and create reports for traffic engineers...
, that ran on a PDP-10
PDP-10
The PDP-10 was a mainframe computer family manufactured by Digital Equipment Corporation from the late 1960s on; the name stands for "Programmed Data Processor model 10". The first model was delivered in 1966...
time-sharing
Time-sharing
Time-sharing is the sharing of a computing resource among many users by means of multiprogramming and multi-tasking. Its introduction in the 1960s, and emergence as the prominent model of computing in the 1970s, represents a major technological shift in the history of computing.By allowing a large...
computer. He adapted this emulator based on the Altair programmer guide, and they developed and tested the interpreter on Harvard's PDP-10. Harvard officials were not pleased when they found out, but there was no written policy that covered the use of this computer. Gates and Allen bought computer time from a timesharing service in Boston to complete their BASIC. They hired Harvard student Monte Davidoff
Monte Davidoff
Monte Davidoff is an American computer programmer. He graduated from Nicolet High School in Glendale, Wisconsin in 1974. He went on to Harvard University, where he majored in applied mathematics, the department at Harvard that, at the time, included computer science. He also worked at WHRB, the...
to write floating-point arithmetic routines for the interpreter, a feature not available in many of its competitors.
The finished interpreter, including its own I/O
I/O
I/O may refer to:* Input/output, a system of communication for information processing systems* Input-output model, an economic model of flow prediction between sectors...
system and line editor
Line editor
A line editor is a text editor computer program that manipulates text primarily by the display, modification, and movement of lines. Line editors precede screen-based text editors and originated in an era when a computer operator typically interacted with a teleprinter , with no video display, and...
, fit in only four kilobytes of memory, leaving plenty of room for the interpreted program. In preparation for the demo, they stored the finished interpreter on a punched tape
Punched tape
Punched tape or paper tape is an obsolete form of data storage, consisting of a long strip of paper in which holes are punched to store data...
that the Altair could read and Paul Allen flew to Albuquerque.
On final approach, Allen realized that they had forgotten to write a bootstrap program to read the tape into memory. Writing in 8080 machine language, Allen finished the program before the plane landed. Only when they loaded the program onto an Altair and saw a prompt asking for the system's memory size did Gates and Allen know that their interpreter worked on the Altair hardware. Later, they made a bet on who could write the shortest bootstrap program. Gates won.
Versions and distribution
As they expected, the Altair was very popular with hobbyists such as the Homebrew Computer Club
Homebrew Computer Club
The Homebrew Computer Club was an early computer hobbyist users' group in Silicon Valley, which met from March 5, 1975 to December 1986...
. Altair BASIC, as MITS's preferred BASIC interpreter, was also popular. However, the hobbyists took a "share-alike" approach to software and thought nothing of copying the BASIC interpreter for other hobbyists. Homebrew member Dan Sokol was especially prolific; after somehow obtaining a pre-market tape of the interpreter, he made 25 copies and distributed them at the next Homebrew meeting, urging recipients to make more copies. Gates responded in 1976 with a strongly worded Open Letter to Hobbyists
Open Letter to Hobbyists
The Open Letter to Hobbyists was an open letter written by Bill Gates, the co-founder of Microsoft, to early personal computer hobbyists, in which Gates expresses dismay at the rampant copyright infringement taking place in the hobbyist community, particularly with regard to his company's...
that accused the copiers of theft
Theft
In common usage, theft is the illegal taking of another person's property without that person's permission or consent. The word is also used as an informal shorthand term for some crimes against property, such as burglary, embezzlement, larceny, looting, robbery, shoplifting and fraud...
and declared that he could not continue developing computer software that people did not pay for. Many hobbyists reacted defensively to the letter.
Under the terms of the purchase agreement, MITS would receive the rights to the interpreter after it had paid a certain amount in royalties. However, Microsoft had developed versions of the interpreter for other systems such as the Motorola 6800
Motorola 6800
The 6800 was an 8-bit microprocessor designed and first manufactured by Motorola in 1974. The MC6800 microprocessor was part of the M6800 Microcomputer System that also included serial and parallel interface ICs, RAM, ROM and other support chips...
. When they decided to leave MITS, a dispute arose over whether the full amount had been paid and whether the agreement applied to the other versions. Microsoft and MITS took the dispute to an arbitrator, who much to Roberts' surprise decided in favor of Microsoft. BASIC interpreters remained the core of Microsoft's business until the early 1980s, when it shifted to MS-DOS
MS-DOS
MS-DOS is an operating system for x86-based personal computers. It was the most commonly used member of the DOS family of operating systems, and was the main operating system for IBM PC compatible personal computers during the 1980s to the mid 1990s, until it was gradually superseded by operating...
.
Further reading
- Cringely, Robert X.Robert X. CringelyRobert X. Cringely is the pen name of both technology journalist Mark Stephens and a string of writers for a column in InfoWorld, the one-time weekly computer trade newspaper published by IDG.- Biography :...
. Triumph of the NerdsTriumph of the NerdsTriumph of the Nerds: The Rise of Accidental Empires is a documentary film written and hosted by Robert X. Cringely and produced for British television by Oregon Public Broadcasting. The title refers to the 1984 film, Revenge of the Nerds, and the documentary itself is based on Cringely's book...
. PBS, 1996.
External links
- Altair BASIC source disassembly, compiled by Reuben Harris and archived at archive.org