Basica was the name chosen by Microsoft for the BASIC interpreter to be bundled with the original IBM PC and subsequent copies of IBM PC-DOS (also at the time written by Microsoft). Also known as "Advanced Disk BASIC", to distinguish it from Cassette Basic or other ROM-based BASIC interpreters.

Here's what the version that came bundled with PC-DOS 3.2 on my 8088-based PC in 1987 looks like:


BASIC 3.20 VER. 1.04F

(C) Copyright Microsoft 1986
Created: 17-Oct-86
61411 Bytes free
Ok_







1LIST 2RUN 3LOAD" 4SAVE" 5CONT 6,"LPT1 7TRON 8TROFF 9KEY 0SCREEN

See GW-BASIC, QuickBasic, and QBasic for some more history and opinions of Microsoft's implementations of the BASIC programming language.