Retro Challenge 2014

I have always wanted to enter Retro Challenge, ever since I first heard of it nearly 24 hours ago. I followed a link that took me to and I read up on what it was all about, scrutinised the rules and checked out what others were doing. I quickly came to the conclusion that I could give this a thing a go.

All I needed to do* was come up with a suitable challenge for myself.

I have decided to make my name appear in LED lights.

So an email was sent to the competition organisers;

Hi Retro Challenge!

I’d like to enter the 2014 Summer Retro Challenge please!

The challenge that I have set myself is to make my name appear in LED lights.

Ok, so that might not sound too difficult, but I’m going to try and do it totally in Z80 assembly language. On a real Z80 computer. That I’m going to have to build. And design. And burn eproms and connect I/O chips and wires and LEDs and stuff. Oh, and I’m not a programmer, and have never done any Z80 assembly stuff.

Does that sound like fun?

I’ll be documenting my progress on my blog as I go along. And probably tweeting about it from @semachthemonkey

Hope that sounds ok

This will be resurrecting the breadboard BASIC Z80 computer I built over Xmas last year, but I’ll be transferring it to printed circuit boards – I say ‘boardS’ because I’m planning on a modular arrangement with a backplane for the bus. Kind of like how old computers were built back in the day, only cheaper with less specialised connectors.


It will mean I have to do battle with KiCad again, and as I’ve only designed 3 PCBs before, this in itself is quite daunting. Then, of course, I’ve got to actually get the boards made. Given that the competition is only a month long, this will be the biggest bottleneck. I will have to rush the PCB design to get them made, however, I can’t afford to make mistakes as there’ll be no time to respin any of the boards.

Assembly and testing of the boards should be fairly straight forward, and I’ve already got the backplane and a suitable enclosure lined up

Then there’s the programming. Oh, programming. Sure, I can copy & paste & tweak Arduino sketches to do what I want, but that doesn’t mean I’m a programmer. And I’m certainly not a assembly language level programmer. So, getting to grips with that while waiting for the boards to be made up will keep me busy.

Then, of course, I’ve got to find some suitable LEDs, and connect them to the hardware I’ve made. I got my breadboard Z80 to control a 7 segment LED display and a bargraph using BASIC, so it can’t be too hard, right? I think there’s a bunch of 8×8 LED matrix boards at Nottinghack that I can borrow, so I guess I’ll try to use those.

Of course, the biggest challenge for me is blogging all of this. As regular visitors to my blog will realise, there’s not much point regularly visiting it because stuff doesn’t get blogged very often. So I’ll have to make a super big effort in July.

Wish me luck!

* Actually, just coming up with a challenge isn’t all I need to do. I still have to enter, and, more importantly, complete what I set out to do!