Monthly Tag


Have some fun! Explore the 145 articles tagged with monthly.

A Trip Down Memory Lane: Recreating “I Was Here” in ZX81 BASIC

Here, ZX81 screenshot, 2023 by Steven Reid

A recently posted meme reminded me of the silly things we did on computers. In the early eighties, most computers came with BASIC as their default OS. A common starting point was a s simple “hello world” program. But almost as often, someone wrote something a bit more personal. This is my tribute program to the “I was here” concept of those days.


How to Create an Infinite Maze on the ZX81

Infinite Maze, ZX81 Screenshot, 2023 by Steven Reid

I saw the Commodore 64 maze generator for years, but ignored it on my ZX81 for different reasons. For one, the characters needed didn’t exist on the ZX81 keyboard. The other was the lack of automatic scroll. Undeterred this month, I created my own version in Sinclair BASIC. I’m quite happy with the results, even if not quite the same.



Chunky Graphics for the ZX81: A New Way to See the Mandelbrot Set

Mandelbrot Set with Chunky Graphics, ZX81 Screenshot, 2022 by Steven Reid

After completing my Chunk Graphics mode, my thoughts went to how best to use it. My first idea was something new, such as a flight simulator. After pondering, I stuck with something current by modifying my Mandelbrot Set program. With three gradients, it would be an interesting use of the mode.


Exploring Chunky Graphics: A New 3-Color Screen Mode for ZX81

Chunky Plot, 2022 by Steven Reid

Out on a run back in November of last year, I had this idea to create a 3-color screen mode of the ZX81. The idea was to use the checkered, or gray, graphic characters to add a third color. After reading about the C64 color modes, I called it chunky graphics as an homage to its wide pixel format. The pixel’s are chunky due to the 2x1 ratio and not being square. Let’s dig into the details.


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.


ZX81 Digital Rain: A Retro Display of the Matrix Code

ZX81 Rain, Chroma ZX81 Screenshot, 2023 by Steven Reid]

The holiday's provided me a nice break to enjoy writing code. During that time, I revisited my digital rain program. For ZX81 Rain, I cleaned up the colors and added a little randomness to where the drops start. Nothing super exciting, but the overall effect is much nicer and looked good in both black/white and color on the ZX81.


Playing With BASIC by Revisiting My Retro E.T. Game for the ZX81

E.T. 23, Getting a Phone Piece, ZX81 Screenshot, 2023 by Steven Reid

I had this idea the other day. One of the problems I’ve had with the ZX81 is printing numbers, which is pretty slow. Due to this, many of my games avoided printing them. delaying showing score until after play has ended. My idea was to try to find a way to speed that up. Not only did I find a way, I decided to implement it in an older game of mine: E.T.


Let’s Have Fun Playing Snake on the ZX81

Snake! Growing Screenshot, 2022 by Steven Reid

I’ve been on a retro computing binge lately and was recently watching one on programming on what it was like to program in the 80’s. Having lived and programmed during that time, I know full well what that was like. But the narrator was showing off an Apple ][+, a computer I didn’t own. Although I programmed on an Apple ][ in high school, my memory of it is vague at best. But what was really interesting was what he was programming a snake game. Being something I’d never tried myself, I thought now would be as good time as any.


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 little BASIC fun with Mandelbrot Sets

Mandelbrot Sets, ZX81 Screenshot, 2022 by Steven Reid

Fun with Mandelbrot sets. I never thought I’d say that, but here I am doing just that on the ZX81. I ran across some fun discussions on them. They are often used as benchmarks, but I just wanted to create some interesting pictures. This is my version using Sinclair BASIC that creates a few interesting ones.



Wasting Time Watching Circles in This ZX81 Demo

Circles, ZX81 Screenshot, 2022 by Steven Reid

I ran across a ZX81 forum post showing a fast way to print a circle in BASIC. It was based on an article for the Atari back in 1983. I was surprised how fast the routine was and wondered how it would in assembly. Long story short, I built a screen saver for the ZX81. Sure, the ZX81 really didn’t need one, but the circles are fun to watch.




Wandering Down the ZX81 Road

Road, ZX81 Screenshot, 2022 by Steven Reid

I had this idea on Sunday that led to today’s program—more about that in a minute. One of those sit down and do it programs, I banged this out pretty quick yesterday. Not wasting time, I decided today I’d share it. Road is a very simple program that I never intended to make. But here it is, so lets talk about it more.



Adding More Movement to My Running Game

Run 2 ML, ZX81 Screenshot, 2022 by Steven Reid

Well, hard to believe we are turning the corner on March and heading into April. Spring is edging its way in and it is time to get outside and work in the yard. This made me want to kick my ZX81 program to the curb, but it didn’t feel right. So, I bundled up my current progress on Run.


Working on Bones for a Future ZX81 Game

Run ML, ZX81 Screenshot, 2022 by Steven Reid

For some time now, I’ve wanted to build a running type game. The kind where there is a single key to press and releasing it makes you take an action. There are lots of variations on this theme, and it seemed like something fun to try. Idea in hand, I began by building out a rough look for the game.



Digger Deeper Into My Water Bug II Game for the ZX81

Water Bug II, ZX81 Introduction Screenshot, Steven Reid, 1984

Now, Water Bug II is an interesting game for me. I was so excited when completing the first version, that I wanted to build another version with ten more boards. The funny thing is, the games look a lot alike. In fact, if you weren’t paying attention, I wouldn’t be surprised if you thought you were playing the same game. Let’s dig deeper on both the similarities and the differences.


Water Bug Was My Attempt at a ZX81 Action Game

Water Bug, Board 1 ZX81 Screenshot, 1984 by Steven Reid

For most of the day, I’ve been thinking about my Water Bug game as I never really gave it a proper write-up. Finally got around to playing it again, I was surprised to find elements in that I thought were unique to Water Bug II are actually in this version. That made me want to walk through each board, understanding better what I had done, what worked, and what didn’t. Let’s dive right in.


An Early and Bad Attempt at a Yars’ Revenge on the ZX81

Yars’ Revenge, a ZX81 Screenshot, 1983 by Steven Reid

Like many teenagers in the early eighties, I was playing video games on my Atari VCS. Yars’ Revenge was a popular purchase, and I spent many hours dodging that stupid missile and trying to take down the shields of the Qotile. It then should come at no surprise that I tried to recreate that game at 13. My attempt on the ZX81 didn’t look horrible, but it sure played bad. Let’s see how much.