For many home-computer owners, BASIC was the first program they met and the first language they used. Microsoft BASIC supplied interpreters for several of those machines. Its family history begins with Altair BASIC, then branches into versions adapted to different processors, memory budgets and hardware.
The connection is visible in Applesoft, Commodore’s BASIC V2, the Color Computer and MSX. It explains familiar statements across those systems, while leaving plenty of ways for a listing to fail on the wrong one.
The terminal becomes a programming environment
MITS’s 1975 Altair BASIC Reference Manual teaches immediate commands alongside stored, numbered program lines. The user can enter a calculation directly or build a program to run later. The manual covers loading and initialisation as well as statements: BASIC needs a working machine, memory and a terminal interface before the conversational prompt exists.
Its 4K, 8K and Extended versions do not all supply the same facilities. Even within the first product, the memory available for the interpreter shaped the language a customer could use. The appendix on converting programs from other BASICs makes compatibility a practical editing task, rather than a guarantee attached to the word BASIC.
The adaptation reaches into the program
Apple’s Applesoft II Reference Manual carries Microsoft’s copyright alongside Apple’s and documents graphics operations specific to the Apple II. Sony’s MSX manual supplies its own screen and music operations. These extensions make the language useful on the machine, but make hardware-dependent source less portable.
| A familiar part of a listing | What still needs checking |
|---|---|
| Arithmetic and loops | Numeric rules, limits and dialect syntax |
| A graphics or music statement | Whether that command exists and what it controls |
PEEK or POKE |
The destination’s memory map |
| A saved program | Token representation and file format |
The distinction is especially visible between Dragon and Color Computer BASIC. Related hardware and a Microsoft language ancestry do not erase their different keyword encodings and system conventions.
Microsoft BASIC was a family of implementations and adaptations. Its reach made ideas and programming habits travel; it did not give every computer the same screen, sound chip or memory layout.
Sources
- MITS, Altair BASIC Reference Manual, 1975, including version and conversion appendices. Original manual.
- Apple Computer, Applesoft II Reference Manual, August 1978: title pages and machine-specific statements. Original documentation.
- Sony, MSX-BASIC Programming Reference Manual: graphics and PLAY. MSX documentation archive.