MicroAce

The MicroAce was an unauthorized copy of the Sinclair ZX80 and was only sold in the USA as a mail order kit. Like the ZX80 it had 1K of RAM but could be expanded to 2K by adding 2 RAM chips and 1 logic chip, as shown in my machine.

CompShop/MicroAce had a history of copying, having previously made a copy of the Ohio Scientific Superboard II called the Compukit UK-101. Next they copied the ZX80, thus saving on development costs. The ROM too was a copy of that of the ZX80, but the bottom right pins (D3 and D4) were swapped, making it look like the binary content of the ROM was different.

Because of the seemingly different ROM, MicroAce claimed their machine was different as well. Sinclair sued them for breach of copyright. Two items were put up in court: the keyboard and the ROM. The judge said that the ROM was not copyrightable as he nor anyone else could read the ROM. However the judge did see that the keyboard was idential and thus Sinclair and MicroAce settled out of court for around £15,000 cash, allowing them to market the MicroAce with certain restrictions: no advertising in publications where Sinclair ran advertisements, not selling it in the UK and only offer it as a kit.

In August 1981 the MicroAce was phased out. Bill Clark of MicroAce said that Sinclair didn’t renew the license. Plans for a kit using the ZX81 ROM were scrapped as MicroAce couldn’t complete with the ZX81 in price.
They did continue to sell the ‘flicker-free’ board for the MicroAce and the ZX80.