Much nostalgia. The TI-83 Z80 was how I learned assembly as a teenager, so I could write better calculator games than was possible with TI Basic. Many others here had a similar experience, I’m sure. It’s been a couple decades, but I’m sure I’d still remember most of it if you put me down in front of a bunch of Z80 asm code.

One thing that I remember vividly was you had no MUL or DIV, so you have to implement them yourself with shifts, adds, subtraction, etc. This was an extremely useful learning experience