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[grsbanks]

The ZX-81 is the machine that I cut my programming teeth on so when the "Speccy" came out I couldn't resist making it my own by customising a load of things on it.

First thing I did was write a Z80 assembler/disassembler in BASIC. I then used it to rewrite it in assembly language and promptly disassembled the on-board ROM.

With the information I had from that, I first accelerated the tape I/O about threefold. I also ripped out the disk I/O section knowing that I would never need it and used the space freed up to rewrite the floating point arithmetic routines and replace the awful 40-bit "precision" (I use that term loosely) ones with my own custom-built 64-bit precision.

All of these alterations were burned to an EEPROM that I mounted in place of the original ROM in the machine.

Those were the days!