BASICA
BASICA is an implementation of BASIC.
Other implementations of BASIC.
BASICA is a BASIC interpreter developed by Microsoft and included with early versions of PC-DOS. It requires ROM BASIC (a BASIC interpreter contained in a ROM chip; a standard feature of the earliest IBM PCs) to function correctly. After a few years, BASICA was superseded by GW-BASIC.
GW-BASIC
GW-BASIC is identical to BASICA, except that where BASICA requires ROM BASIC, GW-BASIC is entirely contained within the interpreter itself. It was included with several versions of DOS. GW-BASIC was eventually superseded by QBasic.