All this brings up long subdued memory .... my HP-25 ,which had cost me one months work during school holidays.. I still
remember when I got payment and the next day walked into
the shop and told the perplexed salesperson : I want this!
He thought nobody in his right mind would buy a calculator without an equal sign button.
Anyway I used it from 1975 to abt 1993 when the battery
leaked .