Today, I did a thing. I bought a 3D printer for the purpose of printing the badge for the Commodore 1541 disk drive. Yes, it is overkill, but I’ll use it later. I feel justified.
Drawing the Mono Lisa on the ZX81
Sometimes a small ZX81 program can still feel like a magic trick. My latest program, MONO LISA, builds a simple picture of the Mona Lisa from a single encoded string using a compact run-length encoding (RLE) style routine. It is definitely slow, but that is part of the charm as you watch the image draw itself across the screen.
Can You Keep Up with Lift, My ZX81 Elevator Game
This week I received a new ZX81 book I purchased on eBay called "Timex Sinclair 1000 Programs, Games, and Graphics." A little graphic program in the back of the book inspired me to create a game called Lift. Can you catch the items before they fall? Let’s dig in.
Building a ZX81 Intro Screen for Wolf, Goat, Cabbage
When I first converted Wolf, Goat, Cabbage to the ZX81, I wanted to include an intro screen. Sadly, I didn’t get around to it at the time. This month, I finally circled back and it turned into quite the journey.
Trap or Gold Is a Simple ZX81 Game of Chance With a Twist
I was pursuing ideas for a simple role-playing or fighting game. The one I landed on was the concept of a single treasure chest. It fit the retro-computing theme perfectly. Trap or Gold is a simple game that doesn't need fancy graphics, speed, or memory — yet it’s still fun.
Bringing My Atari 2600 Joysticks and Paddles Back to Life
I recently got back into retro hardware. My starting point was gaming, as I ordered one of the new Atari 7800s that plays the old cartridges. In my haste to grab a few games, I inadvertently purchased a complete 2600 with controllers. I’ll blame travel and lack of sleep for missing that detail. But it gave me the opportunity to attempt something I’ve never done before: restore the controllers.
Are You Fast Enough to Beat My ZX81 Duck, Duck, Goose Game?
Every once in a while, a small, silly idea turns into a surprisingly fun little project. That’s exactly what happened with my latest ZX81 experiment, a reaction-based game inspired by the old nursery rhyme: Duck, Duck, Goose.
Building a Flip-Style Digital Clock on the ZX81
I’d been thinking about writing a better clock program for the ZX81 for some time but never acted on it. That is, until yesterday when I saw a flip-style digital clock program on the C64. The result is a sort of digital flip clock program for the ZX81 that ended up being quite a fun journey.
Experimenting with Binary Space Partitioning on the ZX81
I thought I’d try something a bit different this month. I’d been looking at different ways to build maps for years but never really did much with them. After watching a video on binary partitioning, I decided to see if I could build a simple map builder on the ZX81. This is the result.
Drawing a Twisted Cylinder on the ZX81
I wrote this back in August and I’m finally getting around to publishing it. It was first shared in my BASIC group, but the ZX81 lacks a lot of the functionality needed for it to run well. Undeterred, I hacked at the program to not only display the twisted cylinder, but also add a bit of randomness to the demo.
Fun with DATA — Building a Blocky World Map on the ZX81
I’d seen a few different BASIC programs that print out a map of the world. Generally blocky, they still looked decent, but much of the data was too big for the ZX81—until I ran across a C64 version based on a Spectrum program. Examples in hand, I built a version for the ZX81.
Speeding Up Truchet Tiles on My ZX81 with Machine Code
Having finished my last Truchet tiles program in BASIC, I wondered how fast it would run in machine code. Soon afterward, I gave it a try, writing a version that runs significantly faster than the BASIC one. Let’s dive in and see how it works.
Exploring Truchet Tiles on the ZX81 with BASIC
Sometimes ideas drop right into your lap. In the case of this month’s program, it was a mix of a post and a video that led me to this Truchet animation. A simple concept, but it worked way better on the ZX81 than I expected.
Recreating Font Art on the ZX81—With Some Limits
It’s funny how a random video can spark an idea. One moment I’m watching someone play around with ASCII art, and the next I’m thinking, “Hey, I could make something like that on the ZX81.” That little spark turned into a weekend project: a simple banner program using different fonts. How fun!
A ZX81 Puzzle Makeover: No More INPUT Drama
This month’s program is a bit of a departure. It is a take on the classic "Wolf, Goat, Cabbage" puzzle. The twist is, I didn’t write this one. Instead, I decided to update it to make the interface a bit easier to use. Let’s dive into the code.
Castle Quest Was My Late-Night ZX81 Adventure with AI
With little time lately, I decided to explore some Generative AI ideas to flesh out new concepts. I’ve dabbled in vibe coding for some time now and thought I’d see how the models would do with adventure-style games. One of the results of that was Castle Quest, a small text adventure for the ZX81.
A New Take on the Infinite Maze for the ZX81
After updating my print scroll routine, I started thinking about how I could use it to create a different version of my infinite maze program. The original used graphic characters and spaces since the ZX81 lacked a backslash. This new version takes a different approach, using alternate graphics to build a more visually interesting maze while leveraging a better machine scrolling routine.
Making Time for a Little Life on the ZX81
I’d read about and studied cellular automata but had never programmed any simulations for them. Conway’s Game of Life is the go-to simulation and something others had already implemented on the ZX81, even when I was a kid. I finally got around to typing in some of those programs but found them slow. My version aims to correct that.
A Present On The ZX81 For VC3 2024
Another year and another Vintage Computing Christmas Challenge (VC3 for 2024). I rushed a bit to get mine in so I do feel it wasn’t as short as possible. I did take a somewhat unique route to solving the problem which makes the build more interesting. I made an auto-run version for Present so you could see it in action.
Turning Hello World into a Creative ZX81 BASIC Program
The year is almost over and time to close out the year with a short program. Watching some videos on character displays in UNIX, I was inspired to create my own version of Hello World. This version scrolls through a stream of random digits until the message is displayed. How fun is that?
Making a better Mandelbrot Set on the ZX81 using High Resolution Graphics
One thing I hadn’t done before on the ZX81 was hires graphics. There are numerous reasons, but in general it was because I hadn’t tried. That changed after being encouraged in my ZX81 group to use with with Mandelbrot Set program. So I did.
Print Like a Pro on the ZX81 with This Updated Smooth Scroll Routine
After wrapping up the last print scroll routine, I immediately dove into improving it. While functional, the original version felt a bit limited. With this update, you’ll find more flexibility in printing displays, though at a slight cost to speed.
Living Dangerously With Math by Running the Collatz Conjecture on the ZX81
As plans go, I actually have a few programs teed up to share. Many are smaller programs that I could work on here and there. Occasionally, I run across an idea that upends those plans and I end up going another direction. So, here we are in September with a math program for the Collatz Conjecture.
Writing a Utility Program for the ZX81 Was Such Fun
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
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.