6502 VS sixty5o2

The Apple 1 ROM is quite a tight piece of coding. Just 256 bytes which implements basic console IO, and memory editing in hex. And still two bytes left over.

One version with lots of comments: https://github.com/jefftranter/6502/blob/master/asm/wozmon/w...

You can see a classic assembly language space optimizing trick at PRBYTE. It first prints the upper half of the byte in hex with call to the PRHEX procedure, then falls through to PRHEX again to print the second half. Two entry points to a common routine.

The First Book of KIM programs

For a command line program I started out with getting WOZMON working and then began adding more capabilities similar to the Apple II system of old. I got tired of adding one-off functionality and discovered Forth when looking at programming languages suited for systems with limited resources. Look into TaliForth2 to get up and running fast on your 6502. The full program requires 24k ROM but can be slimmed down to fit in 16k pretty easily. I was inspired so I wrote my own Forth 2012 Standard version over the summer.

Jeff Tranter has a github with a ton of stuff 6502, including a mini assembler. Many others out there as well.

In my build. I combined it with Sixty502 a bootloader with helpful menu in LCD and buttons.

Here's a kernel that works with the Ben Eater style breadboard one and runs the LCD display: Sixty5o2

I use.the sixty5o2 mini os which allows me to load programs directly to ram. https://github.com/janroesner/sixty5o2

We initially started with a small operating system for Ben Eaters 6502 breadboard computer a Youtube video and I personally had so much fun with it, that when I quit a long term contract with a really well paying client, I did not have to think twice.

https://github.com/janroesner/sixty5o2/ provides some means of serial comms using the Arduino Mega of Ben's package. Can be rewritten to do anything with the data on 6502 side.