ZX81 Computer


Showcasing monthly programs, a retro look at my my first computer, page 3.

How to Build a ZX81 Ultima Game Part 2: Gem Quest

Gem Quest, ZX81 screenshot, Steven Reid, 2016

After sharing Tiles, I started to dig into my previous attempts at building an adventure game. Digging through my past research, I thought about encoding the world differently. Sadly, my experiments using MCODER failed. This spurred me to try assembler again and, to my surprise, build a good start to my game. But first, a trip down memory lane and review my first attempt at building Gem Quest.


How to Build a ZX81 Ultima Game

Tiles, Creating World ZX81 screenshot, Steven Reid, 2013

In 2012 I wanted to see if I could make an Ultima style game on the ZX81. I had an ambitious plan centered on the tile based graphics. After a few months of testing, I was able to create a working prototype called Tiles. Although the game isn’t done, the idea behind it shows promise. You can move around the map using the standard ASDW movements. Other commands are placeholders for what could be. This article explores how Tiles came to be.


How I Used My ZX81 to Draw the Iconic OP Logo

OP, ZX81 Screenshot by Steven Reid, 2020

As 2020 wound down, I had a couple of different ideas for new ZX81 programs. Most of them were graphic programs of various sorts. Themes ranged from dumpster fire pictures, an advent calendar, a virus action game, to a solo RPG. Although they were all great ideas, I didn’t think I’d get any complete enough to publish. In the end, I decided to enter in one of my old graphic programs of the Ocean Pacific logo.


Creating Charts on Your ZX81 Couldn’t Be More Simple

Charts, ZX81 Screenshot of iPhone Data by Steven Reid, 2020

As usual, I procrastinated a bit in finishing my ZX81 program for November. Between holidays, work, and NaNoWriMo, I didn’t get around to it until this last weekend. I decided to try something a little different for this month’s program. The program itself, Charts, is a simple line graph plotter—spelling and bugs galore. As interesting as that program is, the real story is how I entered it.


Entering a Program Shouldn't Be This Frustrating

Star Probe Redo, ZX81 Screenshot by Steven Reid, 2020

Back in July, I made a mistake and entered in Star Probe again. I had forgotten that I’d already shared it. But, unlike my first attempt, I had taken a different approach which made it a much different game. Jumping ahead, I decided to finish what I started. Here is Star Probe Redo, an updated version as October’s program.


Here Is a Silly Test Program for the ZX81

Test, ZX81 Screenshot by Steven Reid, 2020

September proved to be a rather busy month, at work and home. It isn’t unusual for me, and I usually find time to throw a render or program together. As this month closed, I found myself in need of a program to share and not a lot of time. While cleaning up a few things on my laptop, I found this little test program I wrote last month that fit the need.


Here Is My Crazy Idea to Make a ZX81 Game with a Printer

Printer Car, circa 1983, ZX81 Screenshot by Steven Reid

Back in the day I learned to program on school PDP-11 with a 6 teletypes and a CRT attached. I was still in computer club at the time, thinking the 8" floppies were pretty cool. To my despair, the poor thing died that Summer and, when I took my programming class, it was on an Atari 800. But the programs I wrote the previous year stuck with me. Printer Car harkens back to those days.




A Silly Little Code Hack For The ZX81

Code Searcher, 1984, ZX81 screenshot by Steven Reid

I have some sort of fascination with code breaking. A byproduct of all the spy movies I watched as a kid. A friend of my would make spy cases with Lego’s, and I had to build my own of course. I had a wallet with home made credentials and so on. Code Searcher is a bit of a homage to those golden age gadgets of the 60s and 70s.


A Good Start To Adventure Game That Never Was

Wizardry (test), ZX81 Movement Screenshot,  Steven Reid, 1985

When I was a child, I remember going over to a friends house and playing Wizardry on his Apple. Leaving his house, I was super excited about the game I saw. Although my lowly ZX81 was no match, I had visions of creating my own games like it. My attempt, although a test, could have been so much more.


It’s Not Easy Surviving the Waters in This ZX81 Game

Sea Cross, ZX81 Screenshot by Steven Reid, 1985

A bit cliche by 1985, but I was obviously still playing Frogger and the clones it spawned. With all its dodging and moving, the game is classic for good reason. Even in modern times, it has spawned the likes of Crossy Road and other in spirt games. My own attempt, called Sea Cross, finds you trying to get your family safely across the water and home. I doubt you’ll be able to.



Play an Old Star Trek Game That Fails to Be Fun

Star Trek, ZX81 Screenshot by Steven Reid, 1983

Okay, I’ll admit that I was a Star Trek junky. As a kid, I remember eagerly waiting each week to watch reruns of the original series with my family. When 1983 rolled around, I’d watched both of the original movies and owned the comic books that bridged the two. As such, creating a Star Trek game on my ZX81 should come as no surprise.


Can You Run and Jump Your Way through This ZX81 Game?

Bolder, ZX81 Screenshot by Steven Reid, 1985

Running platform games with simple controls were all the rage when mobile gaming got started. Although the themes varied, they all tended to have a few if only on control to them. Some made you press down and release. Others ran on their own, requiring you to press or swipe as needed. My journey into the genre began in 1985 when I wrote Bolder. It may not be popular or exciting, but does show that the concept had roots going deeper than you may realize.


Stop the Missiles from Destroying Your City

Laser Catch, ZX81 Screenshot by Steven Reid, 1984

For November, I found another missile defense game that I wrote a few years back. I honestly didn’t remember this one until I started to play it. Starting off a bit slow, I kept telling myself that it should speed up. And, it did! Guess, my memory isn’t that bad after all. Let’s dig into Laser Catch a bit more.


You Can’t Escape Death in This ZX81 Halloween Tribute

Halloween, ZX81 Screenshot by Steven Reid, 1984

Fall weather brings colder weather, colorful trees, and Halloween! The original movie was still a classic in 1984, even if a few sequels had been released by the time I wrote this program. Lacking the chills of the movie, my Halloween tries to convey the futility of running. Michael always wins.






Shoot the UFOs in This Simple ZX81 Game

Shoot the UFOs in This Simple ZX81 Game

Taking a minor departure this Memorial Weekend, my ZX81 program is actually from my childhood best friend. Neighbors during our time in Italy, Jeremy and I spent a lot of time together playing with our LEGO bricks, D&D, and on our computers. U.F.O is a simple shooter game that takes a unique approach to graphics.


The World Was Doomed And This Is The Result

The World Was Doomed And This Is The Result

The eighties were a turbulent time. Political turmoil grew out of the Cold War, which wasn’t loss on this teenage programmer. The vocal leaders of the US and the USSR bubbled up often in the pop culture of the era and the esclation of war. It shouldn’t be surprising that I’d create an animation depicting that escalation.