I have probably spent more time writing 6502 code than anything else; which is a bit depressing given how painful it was.
I used it because it was the CPU in my BBC Micro (Model B, 32K RAM!) and wrote a number of commercial packages for AUCBE, the Advisory Centre for Computer-Based Education in Hertfordshire, including Quest (a database) and Alpha, a word processor / macro editor.
This was my first exposure to assembly language; I used it on the RML 380Z at school. I remember reading through the entire Zilog guide to Z80 and getting to the end thinking: is that it? So how do you write code? And then having figuring that out. Happy days. Having to move to 6502 for the BBC Micro was painful after the (relative) richness of Z80.
