'''Minimal BASIC''' is a very small subset of the BASIC language. It is specified in ECMA Standard 55, ANSI X3.60-1978 and others. It has a rigorous test suite (initially NBSIR 77-1420 from 1978) to ensure that vendors supplying computer systems to the US Federal government met compatibility guidelines.

The language is very limited:

  • line numbers are required
  • no string manipulation commands
  • all variables must be defined/modified using the LET keyword
  • the only loop structure is FOR … TO … STEP …, with loop parameters fixed at entry
  • all programs must end with an END statement.

Implementations:

  • Microsoft BASIC 5.0 for 8080 (BASIC-80, MBASIC for CP/M - 1981) claims compliance in its manual.
  • [https://jorgicor.niobe.org/bas55/ bas55]
  • [https://buraphakit.sourceforge.io/BASIC.shtml John's ECMA-55 Minimal BASIC Compiler]

Compare with Full BASIC.