@frick, 1986/87 I think
@qubit. No. Z80 had no Multiply. You had to do it with a series of adds and binary rotates (multiply by 2 in binary means shift all 1 and 0 to the left).
Here is someone showing you how to do it on the Z80
IIRC, the Comodore 64 used a "special" 6509 processor called the 6510 which DID have a simple 8bit hardware multiply for one of its registers. It wasnt a "true" multiply, but it helped the coding significantly, meaning long-hand multiply as shown in the link above could be simplified and be about 4-5x times quicker. DIVIDE was still a PITA.
Remember that 8 and 16 bit integer multiple is EASY PEASY compared to the code needed on 8-bit processors to do floating point! Now THOSE PROGRAMMERS I really admire.
Steve Wozniak (and friends). Genius.