Starting a blog!
Published:
I figured it would be fun to keep a record of all the projects I’m working on in a blog format, so I’ve set up the blog page on my website! You’ll be able to access this page at any time by going to ahl27.com/blog!
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Writing a 6502 Emulator, part 2
6 minute read
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Last week, I set up the beginnings of a 6502 emulator, including the core codebase. Unfortunately, a command line application that just runs 6502 assembly code is super hard to debug. The 6502 isn’t equipped with any way to print output by default (unless you’d hook up a 65C22 VIA, but coding that seems tricky), and reading raw bytecode isn’t the easiest thing to do. Other emulators I’ve used (ex. Symon) include a pretty nice GUI to debug applications. I didn’t want to go as far as writing a whole application frontend, but I did think implementing some kind of updated UI would be a great addition for both users and for my personal debugging.
Writing a 6502 Emulator
8 minute read
Published:
I recently watched an awesome video from Computerphile about writing an emulator for the Atari 2600. The 2600 runs off a 6507 processor, which is basically a modified 6502. This got me thinking: how hard would it actually be to write an emulator for a 6502 computer? At this point I’ve already built a computer with one and am close to having a working Forth interpreter–so I’m pretty familiar with how the microprocessor works internally.
6502 FORTH, Part 6: 16-Bit Division
16 minute read
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In my last post, I wrote an algorithm for multiplication. I figured I should at least finish wrapping up the basic arithmetic functions before I go back to writing the main Forth interpreter, so today I’m implementing division.
6502 FORTH, Part 5: Multiplication for Peasants
10 minute read
Published:
It’s been a while since I worked on this project, and I wanted to ease back into it by implementing something auxilliary to get me back into the flow of writing assembly. It turns out the 6502 only has instructions for addition and subtraction, meaning that if you want any higher level arithmetic operations (multiplication, division), they need to be implemented manually. Furthermore, since we’re implementing a 16-bit system, we’ll have to make sure these operations work on 16-bit numbers. This post is going to cover multiplication–I’m still working out the best way to write a division algorithm.