Microsoft BASIC

Microsoft BASIC is the foundational programming language product from Microsoft, first released in 1975 for the Altair 8800 microcomputer. It established the company's early business and became the de facto BASIC interpreter for a generation of 8-bit and 16-bit home computers. Its widespread distribution was crucial in popularizing personal computing and establishing Microsoft as a dominant force in the software industry.

History

The project began when Bill Gates and Paul Allen, inspired by the Altair 8800 featured in Popular Electronics, adapted Dartmouth BASIC for the new Intel 8080 microprocessor. With assistance from Monte Davidoff, who wrote the floating-point math routines, they created the initial 4 KB version. The successful delivery and subsequent licensing of this interpreter to MITS provided Microsoft's first significant revenue. As the microcomputer revolution accelerated, Microsoft licensed versions to major manufacturers like Commodore International, Apple Inc., IBM, Tandy Corporation, and Radio Shack, making it ubiquitous on platforms such as the Apple II, Commodore PET, and TRS-80.

Variants and versions

Early versions were often customized for specific hardware, leading to variants like Commodore BASIC for the Commodore 64 and AppleSoft BASIC for the Apple II. For the IBM Personal Computer, Microsoft supplied IBM Cassette BASIC, IBM Disk BASIC, and the more advanced IBM BASICA. The release of GW-BASIC for MS-DOS and PC DOS provided a standardized interpreter for IBM PC compatibles. This evolution continued with compiled versions like QuickBASIC and the revolutionary Visual Basic, which introduced a graphical user interface and RAD methodology. Other significant branches included Microsoft BASIC for Macintosh and embedded versions for systems like the BBC Micro.

Features and characteristics

As an interpreter (computing), it allowed for immediate program execution and debugging, which was ideal for beginners. It supported standard BASIC keywords like `GOTO`, `GOSUB`, `FOR...NEXT`, and `IF...THEN`. A key feature was its integrated floating-point arithmetic, courtesy of Monte Davidoff's routines, which supported scientific notation. While early versions lacked structured programming constructs, later iterations like QuickBASIC added support for subroutines, user-defined functions, and better control structures. Its simple, line-numbered syntax and direct commands for graphics and sound on many platforms made it highly accessible for hobbyist programmers.

Impact and legacy

Microsoft BASIC played an instrumental role in democratizing programming, serving as the first exposure to code for millions, including future luminaries like Steve Wozniak. Its bundling with nearly every major home computer of the late 1970s and 1980s helped establish a software standard and fueled the growth of the personal computer industry. The language's success provided the financial and market foundation that allowed Microsoft to develop MS-DOS, Windows, and its later empire. Its direct lineage can be traced through QuickBASIC and Visual Basic to the modern .NET Framework and Visual Basic .NET.

Technical details

The original interpreter was written in assembly language for the Intel 8080 to maximize performance within severe memory constraints, often operating in just 4 KB of RAM. It employed a tokenized representation to save space, converting keywords like "PRINT" into single-byte tokens during program entry. The core included a runtime system comprising a command-line interpreter, a list-directed parser, and execution modules. Later versions for 16-bit platforms like the IBM PC expanded its memory model and added support for DOS services, disk file access, and more advanced graphics and sound libraries.

Category:BASIC programming language family Category:Microsoft programming languages Category:1975 software