Hokey cokey, that’s the first 4 printed circuit boards for the RC2014 (Oh, did tell you I’ve named my homebrew Z80 computer “RC2014”? Pretty catchy name, eh?) ordered with OSHPark. If they arrive as quick as other boards I’ve had from there before, then I should have 11 days to get everything put together and working!
All 4 boards look fairly similar, being a CPU board, RAM and 2 variation on ROM, but here’s the 32k RAM board;
Ok, it the 4th day of the Retro Challenge, and this is just a quick blog update about what I did yesterday, which was my 2nd day of doing Retro Challenge stuff. So, yeah, it’s Day Something.
Due to life getting in the way, I didn’t get an early start last night, but I did have time to do 3 schematic and 2 PCB layouts for my Z80 that I’m building.
The first board will be for a 2764 EPROM that’s programmed with Microsoft BASIC. Technically this is not part of RC for me, but I know MS BASIC works on my breadboard Z80 so it’ll be an easy and convenient way to test out the hardware.
So, this is Day 2 of the Retro Challenge. In case you’re wondering what happened to Day 1, well, Day 1 happened to fall on Pub Night, therefore I was better off giving everyone else one day head start than having a go and probably putting myself back at least a week!
If you’ve read my posts on Retro Challenge so far, you’ll know my first priority is to get about half a dozen or so Printed Circuit Boards designed and sent off to the fabricators. The tool I am using to do this is KiCad, and the basic workflow is lay out the electrical circuit schematic, create a list of component, match the components up to footprints, lay the footprints out on a board, join up the various pads then create gerber (manufacturing) files.
I have decided to build my Z80 computer in a modular format, with lots of fairly basic PCBs to make up the whole thing. This should give me flexibility in how I use it and what I do with it going forward. It also makes the boards easy to design and lay out, and, if necessary, easy to troubleshoot too. So, with that in mind, I set out this evening with the goal of making the electrical schematic for at least 5 boards. Starting with the CPU board, which comprises of 1 chip, 1 connector and 1 resistor. Simples!
KiCad uses libraries of components, so when you lay out a circuit you can pick a resistor, a capacitor, voltage regulator etc. It’s got loads of chips in the default library that comes with it, but, as I discovered this evening, no Z80! I tried finding a library on line that had one, but couldn’t get anything that worked. So I had to design my own component – a 40 pin IC! Then, the connector I was going to use was for my Z80 bus, and that had my own designed layout, so that’s another 40 pin component I had to design! Luckily, a regular resistor was already available! So, join the appropriate pins up, and voila! A schematic!
Ok, so tomorrow the Summer RetroChallenge 2014 starts, so I thought it would be a good idea to bring you up to speed with what I’ve got so far so that you know where I’m starting from. I will also outline where I’ll be taking things for the RetroChallenge as well as where this project may go in the future.
So, in December 2013 I started poking around the internets for some ZX80 info, and I stumbled upon Grant Searles website. More specifically, he had the schematics for a Z80 based computer and a ROM with Microsoft BASIC on it. So, over Christmas I got out my breadboards and built it up pretty much as per the schematic.
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 http://retrochallenge.net/ 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.
So an email was sent to the competition organisers; (more…)
