Comment by somat

I was always curious on why their original product, BASIC, did not evolve into a full operating system. Looking at it with the sensibility of a unix affectionado. basic is sort of analogous to the unix shell, a unified interactive user interface and scripting language. This would appear to be a far superior interface than the relatively crippled CP/M inspired DOS command interpreter.

My best guess, memory, on those early microcomputers that consideration trumped any user interface ergonomics and DOS(cough CP/M) used less memory than the BASIC interpreter.