IBM shipped 3 BASIC interpreters with the PC. Cassette Basic, Disk Basic and BASIC Advanced. Cassette BASIC was contained in a 32k ROM. Disk BASIC depended upon

IBM shipped 3 BASIC interpreters with the PC. Cassette Basic, Disk Basic and BASIC Advanced. Cassette BASIC was contained in a 32k ROM. Disk BASIC depended upon cassette basic but added support for floppies and a few other features. It required the cassette basic rom to be present. It was meant for machines with low memory and was launched via basic.com. Once all PCs shipped with more memory by default basic.com became just a launcher for BASICA for batch file compatibility. BASIC Advanced (BASICA) also required the presence of the cassette BASIC ROM. It added additional features above disk BASIC but required more memory. It was originally launched via basica.com. This eventually changed to basica.exe. At this time basica.com became just a launcher of basica.exe. Non-IBM versions of MS-DOS, at least the versions targeted for PC clones, shipped with basic.com and basica.com being launchers for basica.exe. This is true at least as far back as Compaq DOS 1.10. Earlier versions of MS-DOS were branded by OEMs and included versions of GW-BASIC which didn’t make direct reference to GW-BASIC such as the Compaq example you gave. I have a Zenith Z-161 luggable in my collection and the Zenith version of MS-DOS it runs has a BASIC which is gw -basic but reports itself Zenith BASIC and simply includes Microsoft in the copyright notice.