Unfortunately not as hard a constraint... Apparently Sinclair calculator designers learned that the electroflourescent display and another component, could liv

Unfortunately not as hard a constraint... Apparently Sinclair calculator designers learned that the electroflourescent display and another component, could live with the power dropped, sufficient I believe so they could use button cell batteries, so making the (claimed, I can't verify, "smallest calculator" was so hotly contested that that was a large part of a super documentary on the Japanese silicon industry) smallest model at the time. The display, I presume, had a decay for the elements, but what the other component was must go on my too long research todo. Edit: my cherished ef display calculator at about the same time, used a 9v "square" battery, that was fast depleted, faster than my pocket money could withstand, anyhow.