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Have some fun! Explore the 9 articles tagged with assembly.

Writing a Utility Program for the ZX81 Was Such Fun

ML Basic, Print Scroll 2 Output, ZX81 Screenshot, 2024 by Steven Reid

Sometimes, you do things out of necessity. I spent an inordinate amount of time working on adding automatic scrolling to a PRINT command. In fact, I haver another version of my print scroll routine I’ll talk about later. But this is about a utility program. A way to print out BASIC code in hex. And this article is about what I did and why.


Infinite Scrolling on the ZX81 with Machine Code Magic

Print Scrolling, ZX81 Screenshot, 2024 by Steven Reid

Finding inspiration again from my programming groups, the idea of an infinitely scrolling screen of text came up. There were a couple of different solutions posted, some quite ingenious. I had done something similar in the past, but this time I used a bit of machine code magic to create a more flexible solution. The result is Print Scroll.


Meow in Motion: A Z80 Assembly Version of a Classic Cat Animation on the ZX81

Fast Cat (Cat ASM), ZX81 Screenshot #2, 2023 by Steven Reid

After finishing the basic version of the cat animation, I wanted to improve the frame speed. This meant converting from BASIC to machine code. My first thought was to do the conversion with MCODER II. I dropped that idea, deciding to focus on a custom z80 Assembly version. Ergo, cat written in assembly or Fast Cat is, well, a faster version and a bit more.





More Mandelbrot Set Fun in Z80 Assembly

Mandelbrot Sets Machine Code, ZX81 Zooming In Screenshot, 2022 by Steven Reid

Okay, after finishing my BASIC program version of Mandelbrot Sets, I decided I needed more speed. I wasn’t sure if I could write a version in assembly. My concern was the floating point math. After a good amount of research, and trial and error, I finally got a version working. This is my story.



A Developer Diary in Pictures for Gem Quest, a ZX81 RPG

Gem Quest, Darkness Screenshot by Steven Reid, 3/07/2021

If you’ve been following me the last couple of months, you know I’ve been revisiting Gem Quest. Intended to be an Ultima style game for the ZX81, outside of a few demo’s I really hadn’t gotten far. That isn’t the case now. I’ve spent the last month learning z80 assembly code and hacking my way through the game. Tracking my progress, I’ve been capturing that journey in pictures and movies, which I’ve uploaded into a Flickr album.