There’s this naive concept that these 8 bit microcomputers programming were based in BASIC. The speed of these Z80 chips was 1-3 MHz.

Almost all games and programs in the 8-bit world were written in Assembly. The BASIC interpreter was just used as the bootloader to load and run these programs, BASIC was in fact the shell interface and the toy language, but the assembly programs essentially sold the computers.

If you wanted to do something in these computers, it would have to involve assembly because of BASIC slowness. And there were newbie books about assembly language, assembly libraries, tons of assembly compilers and debugging utilities available anywhere.