ZX81 Computer


Showcasing monthly programs, a retro look at my my first computer., Page 7

E.T. Redux

E.T. MC, Finding a Flower, 2012 by Steven Reid

E.T. may not have been my best game ever, but it was an interesting exercise in 1985. Loosely, and I really mean loosely, based on the Atari 2600 game, E.T. follows the exploits of the title character as he tries to find his way home. Originally written in ZX81 BASIC, I revisited E.T. to better understand how to use MCODER II. I was ultimately successful in compiling it and getting it to run. If you are adventurous, you can compare it to original version, bugs and all. Instructions for E.T. are available off my old ZX81 website.




February’s Program: Light Walls

February’s Program: Light Walls

February is upon us and that means another program of the month. This month it is another one from 1983: Light Walls. In case you hadn’t guessed, it has its roots in Tron. The game requires you to steer right (“.”) or left (“z”) to avoid hitting the light walls. I wrote this program while a friend was over and we took turns trying beat others high scores. Who says you need color and 3D graphics to have a good time! Not convinced. Give it a try yourself and see how good your reactions are.


ZX81 Emulator on Android

ZX81 Emulator on Android

As more and more people turn to mobile and tablet devices for their entertainment and consumption needs, it is becoming harder to share my ZX81 preservation project. I remember how excited I was when I found a Java based emulator that would run my ZX81 programs on the web. Although Java and I haven’t always gotten along, I was happy to be able to show off my programs on the go with nothing more than a browser available. To my surprise, however, Java isn’t even part of the conversation when talking about those on-the-go OS’s like iOS and Android. All that effort isn’t of much use when a large portion of your audience can’t enjoy it. Fortunately, and much to my surprise, I ran across Zed Ex (Beta) in the Android Market. You can also find it on AppBrain.com.


January’s Program: Road Hog

January’s Program: Road Hog

Welcome to the new year! Starting off the second season of monthly programs is January's program Road Hog. Road Hog is a driving game similar to my later Flywheel game. I hesitate to call it a racing game as there is no acceleration. You just move the car left or right using the Z or . keys. The game is pretty easy due to the slow speed of the animation. Go give it a spin.


A New Year of ZX81 Programs

ZX81 Computer

Well, the celebration of thirty years since the introduction of the ZX81 is now over. For the last year I've been bringing you an original ZX81 program each month as a tribute to my first computer. It was a lot of fun typing in those old programs or fixing tape recordings I made back in the eighties. I even rewrote one which brought me back to those old programming days. For those that found your way here, I hope you enjoyed my ramblings about the programs. Perhaps you've learned something or I just invoked a kinship from a fellow programmer.


December’s Program: Creature

December’s Program: Creature

I can’t believe December is here and the year is almost over. To celebrate the last program of the month, I present Creature, an animation program. Unlike many of the smaller programs submitted throughout the year, this one is the largest weighing in at 14KB. Although Creature isn’t as exciting next to more modern computer animations, I still find it interesting to see what could be done with this little machine 26 years ago. Give it a watch, enjoy the nostalgia, and try not to laugh too much.


New RSS Feed

ZX81 Computer

As of today, you can use RSS to subscribe for your monthly dose of ZX81 goodness. I originally hadn’t planned to offer an RSS feed for my ZX81 site. The original goal was to cross-post articles to my main site and rely on its feed for subscribers. Sadly I tend to forget to cross-post.



October’s Program: 1985

October’s Program: 1985

October’s program is one of my later games from 1985 which is aptly named 1985. It has decidedly simple game mechanics. Set in an alternative reality, the Earth is gone in this version of 1985. Humans are colonizing Earth II, but you need to clear the mountains for agriculture needs. Yes, your job is to hit any key to clear the land. Things couldn’t be easier, right?


September’s Program: Odyssey

September’s Program: Odyssey

This month I present another simple game, Odyssey. It doesn't include instructions, so here is a quick synopsis. An evil computer has trapped you in a space ship. To escape, you have to remove the memory boards in order to shut down the computer. Sounds familiar? Obviously this program was inspired by 2001: A Space Odyssey. To play, use “Z” to move left and “.” to move right. Hit the “M” key to remove a memory card. Try to remove all of them in time to beat the computer.


Space Lander 2011

Space Lander 2011

I couldn’t leave well enough alone. All that analyzing and nitpicking of the original Space Lander made me wonder what it might be like if I had rewritten it. Almost 28 years later, here is the reborn version of Space Lander 2011.


August’s Program: Space Lander

August’s Program: Space Lander

Okay, this may not be the large program I promised, but I choose Space Lander for a different reason: it's horrible! Okay, maybe it isn’t that bad, but it definitely wasn’t one of better programs. This was from 1983, clearly one of my earlier attempts. Actually, it is kind of refreshing reminder how much better my programming has become. If this helps others learn, then by all means check out the listing.


July’s Program: Sugar Cube Munch

July’s Program: Sugar Cube Munch

Another simple program. Like many that I wrote for the ZX81, Sugar Cube Munch was small with a singular purpose. In this case, the goal is to eat all the cubes of sugar as quickly as possible. Once all the sugar is eaten, the game is over and the number of turns is revealed. You can give it a try by using the ZX81 arrow keys 5,6,7, and 8 to move around.


June’s Program: Beo One

June’s Program: Beo One

I was searching through my stack of programs and decided to choose a short and sweet program for June. Beo One is definitely short, clocking at just 33 lines of code. Well 35 if you include the two new save and run lines I added. This is a simple talking head graphic program, which is the sweet part.



April’s Program: Sphere

April’s Program: Sphere

I’ve been a bit busy this month so I choose a relatively short program in order to not miss my self imposed deadline. To that end, I present to you April’s belated graphic program: Sphere. This program will easily run on a 2K ZX81. With some trimming, if you are so inclined, it will probably run in the original 1K of RAM as well. Although I doubt too many people with a ZX81 have less than 16K of RAM. Take a look at the listing to get a feel for how small this program really is.


March’s Program: Lock £ Fire

March’s Program: Lock £ Fire

March’s program is Lock £ Fire. I wrote this graphic game in 1985, although I have to admit I don't remember it much. It is a bit hard to play as the keys aren’t very sensitive and the aliens jump around as you try to “lock” onto them. It doesn’t help that I used an odd keyboard layout which adds to the difficulty. The aliens are shooting at your shield and, if they get through, the game is over. Note that you don’t kill the aliens, but they may change their look. When you shoot them enough, the next level starts. Every 10 hits will clear some of your shields as well. Boy, I must have been in one of those moods when I wrote this.


Digging for Old Books

Digging for Old Books

For some time now I’ve listed the ZX81 books I own on my original ZX81 web site, but I hadn’t put much effort in searching the web for them. Mainly this was because I already own them, but mostly because it never occurred to me to do so. I ran across an online copy of Sinclair ZX81 BASIC Programming which made me wonder what other books existed out there. Sadly, my search uncovered very little legitimate books. However, World of Spectrum did have a good number of the books and cover art available.



Major ZX81 Updates

Major ZX81 Updates

A few things have changed over the list eight years. As I wind down the use of my ZX81 site, incorporating it my main one, much of below is invalid. That doesn’t mean that changes weren’t important at the time. Ideas come and go, and it is good to remember where we came from. Below is a recap of what was.


New ZX81 Programs Section

ZX81 Computer

I’ve added a new ZX81 Programs section that lists all of my ZX81 programs available so far. The list includes the name, a brief synopsis, and options to list or run the program as available. I still need to add a more complete description option. The code is there, I just haven't decided how I want to deal with the pictures. But hey, at least you can run every program I had available before, plus a few new ones.


January’s Program: Water Bug II

January’s Program: Water Bug II

I did it! After a lot of recording, cleaning, and tweaking I was finally able to get Water Bug II loaded! Hit the link, wait for it to load, then hit enter to give it a whirl. Then use the 5, 6, 7, and 8 keys to move (left, down, up, right) just as they are on the ZX81 keyboard.