An interesting look at silicon-on-sapphire

[dm319]

I've been following Ken Shirriff's blog since I first read his article on reverse engineering the adder in a 6088 chip. His most recent article looks at a silicon-on-sapphire chip, taking microscopic images of it to see how some of it functions. The chip isn't for a calculator (though I imagine it would be fascinating to see how the BCD processor was implemented), but thought it might be interesting:

https://www.righto.com/2023/12/HP-silico...-chip.html