Traditional assembler, and higher level compilers work with several memory segments, according to intended use. Hence, there is a data segment, a stack segment, a bss,
Could it be because the program code, be it hard-to-read machine instructions, is really the program text - i.e. the text that contains the instructions? The same as when you call a calculus book a text book, although it is pretty hard to decipher unless you are familiar with the mathematical symbols that are the code..