I've been thinking about replacing the ROM in one of my ZX81's by a bigger one, with the option to select part of it. And I was wondering: what would you suggest to put in there as options to select?
Considered including the following:
- Regular ZX81 ROM.
- ZX80 ROM (2x as it's a 4 KB ROM).
- A duo of Forth ROMs: H4th and Tree4th, which seem essentially the same but I'd like the option to check out either 'flavor'.
Which would conveniently fit into a 27C256 (32 KB). But with more ROMs to include, I could go for a 27C512 (64 KB) which also fits in a 28-pin footprint. An EEPROM or even a large Flash EPROM is also an option, but re-writing the contents might be difficult after I'd write eg. a Forth ROM into it. And I'd like to keep the 'select logic' as simple as possible, for example a few pull-up resistors + jumpers on highest address lines.
So: any suggestions on other ROMs to include? Bugfixed versions? Perhaps a ROM that does away with the keyword-based entry method?
