Microsoft BASIC

The Altair BASIC interpreter was developed by Microsoft founders Paul Allen and Bill Gates using a self-written Intel 8080 emulator running on a PDP-10 minicomputer.

[1] The MS dialect is patterned on Digital Equipment Corporation's BASIC-PLUS on the PDP-10, which Gates had used in high school.

[2] The first versions supported integer math only, but Monte Davidoff convinced them that floating-point arithmetic was possible, and wrote a library which became the Microsoft Binary Format.

[1] Altair BASIC was delivered on paper tape and in its original version took 4 KB of memory.

The following functions and statements were available: LIST, NEW, PRINT, INPUT, IF...THEN, FOR...NEXT, SQR, RND, SIN, LET, USR, DATA, READ, REM, CLEAR, STOP, TAB, RESTORE, ABS, END, INT, RETURN, STEP, GOTO, and GOSUB.

The final major release of BASIC-80 was version 5.x, which appeared in 1981 and added support for 40-character variable names, WHILE...WEND loops, dynamic string allocation, and several other features.

Hence, Microsoft's and other variants of BASIC constitute a significant and visible part of the user interface of many home computers' rudimentary operating systems.

[5] IBM's Don Estridge said, "Microsoft BASIC had hundreds of thousands of users around the world.

However, due to the popularity of CP/M, the great majority of Z80 machines ran MBASIC, rather than a version customized for specific hardware (TRS-80 BASIC was one of the few exceptions).

The TRS-80 Model 4 had a newer disk-based BASIC that utilized the BASIC-80 5.x core, which included support for 40-character variable names.

Thus the ability to crunch program lines (without spaces between keywords and arguments) was no longer possible as it had been in Level II.

A modified version published later by OS provider Logical Systems, in the LS-DOS Version 6.3 update, added single-letter access to BASIC control functions (like LIST and EDIT) and direct access to LS-DOS supervisor calls.

The first implementation as a standalone disk-based language system was for Seattle Computer Products S-100 bus 8086 CPU card in 1979.

Later implementations of 6502 Basic (1983–) had many vendor specific improvements; for example later versions of Commodore BASIC had the following: Microsoft catalogs from the 1980s also showed the availability of BASIC-68 and BASIC-69 for the Motorola 6800 and 6809 microprocessors respectively, running the FLEX operating systems, and also mention OEM versions for Perkin-Elmer, Ohio Nuclear, Pertec and Societe Occitane d'Electronique systems.

[11] It seems likely this is what is also the basis for the Microsoft/Epson BASIC in the Epson HX-20 portable computer, which has two Hitachi 6301 CPUs, which are essentially a "souped up" 6801.

However, versions that will still run on modern machines can be downloaded from various Internet sites or be found on old DOS disks.

[13] Small Basic Version 1.0 (12 June 2011)[14] was released with an updated Microsoft MSDN Web site that included a full teacher curriculum,[15] a Getting Started Guide,[16] and several e-books.