I build a kit form of the ZX-81 back in the early 80's. It was a terrific machine for me at the time. Now I think these chips are still sold into traffic lights

I build a kit form of the ZX-81 back in the early 80's. It was a terrific machine for me at the time. Now I think these chips are still sold into traffic lights. Who else here remembers their Z80 opcodes? I remember C8 Return of Zero, and just plain old return, C9. Been a whole though... These days a single line of PHP would bring the Z80 to its knees...