The UK’s Centre for Computing History in Cambridge recently got donation of very early prototype of Sinclair ZX Spectrum from late 1981 or early 1982, by Nine Tiles company responsible for Basic ROM for ZX80,ZX81 and also Spectrum.
The ZX80 and ZX81 basic were written by John Grant. For ZX Spectrum Basic ROM floating-point arithmetic, including trigonometric and other functions was added by Steve Vickers, while software for hardware support was done by Richard Altwasser.
As they want to release ZX Spectrum as soon as possible, the original plan was to ship the machine and to do ROM upgrade later. But this was a bad plan as there were too many machines sold. Nevertheless they included shadow ROM for periphals.
In the end Sinclair launched the Spectrum with not finished ROM, Nine Tiles did continued to work on ROM for some time after launch, but as too many machines had shipped, new code and this prototype were no longer needed.
How ever it would be nice to see what Nine Tiles did in that 3 monhs with Basic ROM.
The UK’s Centre for Computing History in Cambridge have largest computer and video games museum with a uniquely hands on exhibition and if you live in UK make sure you visit it.
They also created a nice video about Sinclair ZX Spectrum Protoype.