83 – 6502

by Administrator. Average Reading Time: about a minute.

One of the first programming environments I worked with was the 6502 CPU and its assembler. I liked it quite a bit better than the Z80 (which didn’t hinder me of course to ask for a Z80 programming book as a birthday gift – my parents surely thought I was crazy)

I never, really really, grasped assembler then (although later, one of my first big software projects was to write the DES encryption for 8051. The only source I found for DES was an obscure paper that described the algorithm in APL. I learned to read APL, and started to implement the algorithm in assembler. Of course there was no good tooling available, so I wrote a 8051 Assembler in Turbo Pascal. And while I was at it, I also wrote a 8051 emulator in Turbo Pascal. I vaguely remember if…then…elsif… elsif… end constructions that spanned several 100 lines of code in the inner loop of the emulator – at that time I hadn’t yet heard of lookup tables.)

But back to the 6502. A couple of years ago, the Visual 6502 implemented the actual gates of the processore in JavaScript, and today I stumbled upon the Easy 6502 introduction to its assembly language (with a high level simulator in JavaScript). (Link via Infovore)

Fond memories, some of the stuff actually came back to me from the hazy mists of my memory.

And boy – am I glad, that there are high level languages these days!

One comment on ‘83 – 6502’

  1. The only fragments I remember:
    A9 00 # LDA $0
    E9 00 # LDX $0

    That’s about it … sadly. Can’t even remember the op-code for BNE. (And I think 00 would be BRK, but it could also have been $02… But I think that was NOP… anyway: Those where the days)

Leave a Reply

  1. Subscribe to this comment