I have a copy of "Tiny" Pascal by Supersoft from 1979 on a cassette tape which was licensed to Tandy Corp and which would load onto a 16KB TRS-80 Model III and allow a bit of room for programming.
One of the great regrets of my life is that when I was doing so and when it would have mattered, I was unaware of the patch for this which would have allowed it to be saved as an executable to a TRS-DOS disk....
Except that wasn't possible. Languages like BASIC and Forth exist because they were the only kind of language implementable in 4K with no disk. Pascal in its smallest form (UCSD p-system) still needed disk overlays. The smallest C compilers were poly phase, needing storage for intermediate state.
Microsoft itself popularized BASIC on microcomputers with its 8080 BASIC, starting on the Altair and ported to everything with A, B, C, D, E, H, and L registers since.
Before then, however, BASIC was already popular on minicomputers as both an introductory language for beginners and a business language; the various "Business BASIC" dialects providing a small-business alternative to COBOL on mainframes with their features for decimal math and ISAM database access.