SR-56C? Interesting idea.

[Peet]

(06-11-2022 05:13 AM)pauln Wrote:  In the TI-57, the display goes black when doing an "expensive" computation such as "88 sin" ...

Many calculators with LED displays from that time behaved like this. My first programmable calculator was a Commodore PR100 and I remembered this behave at e.g. 69!.

BTW, back then I always used the "." as a constant memory simulation.