Sinclair

Retro Challenge 2024/10 - Defeating The Riddler
The schematic for the ZX81 Module I designed in2016 had been designed in a very old version of KiCad, and hadn't survived all the upgrades…
Retro Challenge 2024/10 - Finding a donor
If you remember from my initial post at the start of the month, the first thing that I needed to do in order to make…
Retro Challenge 2024/10 Talking The talk... at 9600
Following on from the failure to get the Portfolio talking directly to the RC2014, I decided to turn my attention to the Cambridge Z88. I…
Retro Challenge 2024/10 - Intro Post
It has been a while since I entered Retro Challenge, but I think I remember what to do. It goes something along the lines of…
Retro Challenge 10/2016 - Still a work in progress
So, who remembers my entry for Retro Challenge in January? It was quite devoid of effort and results I think you'll agree. Well, this time…
Retro Challenge 2016 - My Dog Ate My Homework
So, all the way back in deepest darkest December, I announced I would enter the Retro Challenge 2016 competition that ran throughout January. Those of you that followed by blog or Twitter account when I did this in 2014 will know that I blogged and Tweeted relentlessly for the whole month, but, this time around, almost nothing. Obviously, I'm keeping some secret about an amazing breakthrough or something, right? Well, truth is, I've done almost nothing.
Things started well, and on 1st January, I designed a new backplane for the RC2014. Although I hadn't studied the circuit diagrams for the ZX81, Jupiter Ace or ZX Spectrum yet, I knew that there were resistiors between the Z80 CPU and other devices. The stripboard backplane I'd been using had served me well, but it was time to progress to a better solution, and one that could be adapted better to my needs. Knowing that PCB delivery times could be against me, I thought it best to crack on and get this ordered.
The basic circuit is very very simple - however, I wanted to get this just right, not only for Retro Challenge 2016, but for other possible RC2014 uses. Essentially, there are 8 40 way connectors that are linked straight through - however, the data lines and address lines for the leftmost 2 connectors and rightmost 2 connectors are separated by a pair of pads. These can either be shorted together for up to 8 commoned connectors, or have resistors soldered across them. I also added a power connector and the option of either running 5v directly in to the board, or regulating a higher voltage down via a LM7805.
Retro Challenge January 2016 - Preamble
So, you may well remember that I entered Retro Challenge 18 months ago, and what a fun crazy busy time that was! Well, the January Retro Challenge competition is about to kick off in just over 2 weeks.
If you're not familiar with Retro Challenge, shame on you! But you can de-shame yourself by heading over to http://www.retrochallenge.org/ and seeing what it's all about. Essentially, it's a month long bi-annual competition where the entrants set themselves a goal based around old school computing and blog, tweet and share their experiences. The goals are pretty loose, as long as they are based on something from last centuary (modern emulators of old kit is fine).
The challenge I set myself was to take a breadboard based Z80 computer and bring it to life in modular PCB form in such a way that I could spell out my name on. Have a look back through my blog to see how I did. Spoiler ---->
RC2014 with ZX Printer interface
My original plan had never been to design and build my own computer. I had, however, planned to build a clone of the Sinclair ZX80, which has been on my bucket list of things to own for year, and which I had found plans for online. Whilst collecting the parts and reading up on simple Z80 computers I got kind of sidetracked and ended up with the RC2014.
The heart of the RC2014 is a Zilog Z80 CPU, which is the same one that Sinclair used in the ZX80, ZX81, ZX Spectrum and Z88. If the ZX81 and ZX Spectrum can run a ZX Printer, then surely it follows that the RC2014 will be able to too?