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A few months after Sinclair released its ZX-80, Microace of Santa Ana, California launched a clone of this computer.

It was exactly the same machine, but a minor modification made that it could be expanded to 2 KB of RAM.
The internal ROM was also a pure copy of the Sinclair's original. Sinclair thus sued Microace but met with large difficulties because the judge couldn't seee the ROM content!
Sinclair eventually won because the Microace keyboard was also identical to the ZX-80's and the judge could see it...

Microace then ceased the production of the 4 KB ROM machine but made later an agreement with Sinclair for a licenced version of the ZX-81 to be put on sale only in kit form and only in the USA. Microace also made a 'flicker-free board' for the ZX-80.