Who has a sinclair scientific programmable?

[MinkLib]

The Sinclair Scientific, as widely reported, uses the TI TMS0805 chip, a very clever firmware job from Nigel Searle, reverse engineered by Ken Shirriff of Google in 2013.

But what chip does the Sinclair Cambridge Scientific use? About the same time (later in 1974?) as the Scientific and in the same case, but clearly a very different chip (3v supply instead of 6v, many extra features eg Pi, root x, natural logs).