>>>Not entirely sure, but was it not to move a memory block?
>
>Sure was! Used up HL, DE and BC to do it. Lots of stack operations needed in Z80 Assembly! The one I liked was the Restart Vectors that allowed a jump with one byte rather than three. Can make all the difference when you've got only 16K for everything (or 4K in the Level 1.) One of the RST was left free and entered RAM, the rest had predetermined but useful functions. Just typing this reminds me of the smell of the softback book I pored over when using Edtasm. Those were heady days.

Somewhere in the late 80-ties, I wrote a Z80 compiler that would run a PC. Sure was a lot faster than running it on a MSX. I never used the interrupts AFAIK, I do not think it had many uses on my MSX (guess where it stands for?) computer.

But indeed , those were the days, where programming even the simplest routine could take up a whole day. For example writing a routine to multiply two integers.