GW-BASIC was a dialect of BASIC developed by Microsoft from BASICA, originally for Compaq.
It is compatible with Microsoft/IBM BASICA, but was disk based and did not require the resources of the ROM included on IBM's machines.
It was bundled with MS-DOS operating systems on IBM PC compatibles by Microsoft.
Like other early microcomputer versions of BASIC, GW-BASIC lacked many of the structures needed for structured programming such as local variables, and GW-BASIC programs executed relatively slowly, due to the fact that it was an interpreted programming language.
It did have a large number of graphics commands.