Sinclair ZX Spectrum Prototype

This has been in the possession of Nine Tiles, a subcontract company who had been responsible for the Basic ROM in the ZX80 and ZX81, and finally the Spectrum. Both Steve Vickers and Richard Altwasser left their respective companies to form Cantab, the Basic ROM was never quite finished, with support for peripherals lacking as no working units were handed to Nine Tiles in time. The result of all this unsettled period was that Sinclair launched the Spectrum with an unfinished ROM, Nine Tiles continued to work on it until 3 months after launch, but by then too many machines had shipped, so the new code and this prototype were no longer needed.

Source: www.computinghistory.org.uk