[Piotr Patek] ran into this issue when he obtained an Elektronika MK-85 programmable calculator with a broken CPU. Unable to find a replacement, he decided instead to build a pin-compatible CPU ...

Before Wolfram Alpha, before the Internet, before even PCs, calculations more complex than what could be accomplished with a “four banger” required some kind of programmable calculator.

Parents bought new toys that offered both instruction in arithmetic and other games for their children. A few calculators were programmable, offering an alternative to large computers and to the ...