The PC8300 was announced at the 1983 Consumer Electronics Show. Marketed, and maybe manufactured, by Unisonic, it was a “clone” of the ZX81. The ROM featured a highly similar BASIC but with the character code table moved to the custom chip.
As a clone, it wasn’t particularly compatible with the ZX81:
- the display file appears before the BASIC program on the PC8300
- it’ll load programs but not the variables
- ROM routines are “scrambled,” preventing one from using ROM calls in machine language
- programs with embedded machine language won’t run because they load at a higher place in memory
- the hardware of the display system is sufficiently wonky to preclude simply using a Sinclair or Timex ROM
On the hardware side, it was very compatible: most T/S peripherals could simply attach and work.
A few years after its announcement, the PC8300 showed up in surplus dealer ads, like this one in Byte, for $30.
Fred Nachbaur developed a ROM that offered greater compatibility with the T/S computers. It was a simple, drop-in replacement that offered “90% compatibility.”
