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There wasn't an OS to talk about. The 16kB ROM contained a BASIC interpreter, which was ignored by most applications you would load from the tape. If you wanted
by vetinari 10y ago
There wasn't an OS to talk about. The 16kB ROM contained a BASIC interpreter, which was ignored by most applications you would load from the tape. If you wanted to talk to the hardware (joystick, printer), you did the I/O yourself.
- pjmlp 10y agoThe 16kB ROM BASIC interpreter was the OS! And you surely could not overwrite it.
- vetinari 10y agoNot from inside; but an external device could remap the address range (not that it was made often, except for D40/D80 which did that, replacing microdrive code with a floppy one) and the ZX128, which actually had two ROM banks. There weren't many useful things in the ROM, if you were writing your application. Maybe the font table and tape loader. On the other hand, if you were able to ignore the ROM, you got few bytes more of RAM, because you were able to repurpose the "system variables" area. The biggest "problem" with ROM that you were unable to replace it with RAM (until next reset, for example), thus taking precious 16kB out of 64kB address range.