If you’ve watched my recent video on the Nixie tube clock, you may have noticed that my clock didn’t have a power-on reset capability. It sat there locked up until someone flipped the reset switch. I spent some time looking over the Internet and came up with two options for reset circuits: Option 1: The …
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Z80 retrocomputing 11 – CP/M on the RC2014
In this post, I run CP/M on the RC2014 While browsing around Grant Searle’s website looking at his Z80 projects one day, I stumbled upon his CP/M project and it sounded like a great idea to reproduce this on the RC2014. Motivation CP/M is a disk operating system that was popular from the 1970s to …
Read MoreZ80 Retrocomputing 10 – RC2014 CompactFlash board
In this post, I implement a compactflash adapter for the RC2014 If you haven’t read by first blog post on the RC2014, please start there as it will provide background information, including where I purchased the kit from. Purpose If I think back to my first computing experiences, there was usually some form of storage. …
Read MoreNixie Calculator Update – PCB availability, source code, design notes
The nixie tube calculator project was not funded on kickstarter, and I recall some time ago promising to make the boards and other resources that I used for constructing the prototype available. Well, it’s taken a while but I’ve finally got around to it. I’ve made the boards available on Osh Park, which is the …
Read MoreZ80 Retrocomputing 9 – CTC and dual serial ports for RC2014
In this post, I add a Z80 CTC (counter-timer) and SIO/2 (serial IO) to the RC2014 If you haven’t read my other Z80 retrocomputing blog posts yet, then please start with the first one, Intro to Z80 Retrocomputing, for an overview of the RC2014 platform. Motivation All I wanted to do was connect a GPS …
Read MoreZ80 Retrocomputing 8 – Speech Synthesizer for RC2014
I built a speech synthesizer board for the RC2014 The speech synthesizer IC that I chose is the SP0256A-AL2. One of my reasons for choosing it was that it seemed plentiful on eBay. They’re all fakes though, every damn one of them on eBay, so far as I can tell. 🙁 Fortunately, there is a …
Read MoreSP0256A-AL2 speech synthesizer chips: Genuine vs Counterfeit.
All I wanted to do was build a speech synthesizer… To make a long story short, I’ve ordered chips from three difference China eBay sellers, and have received three different sets of chips that don’t work right. The first set of bad chips Here’s the first one: This one actually turned out to be an …
Read MoreZ80 Retrocomputing 7 – RC2014 DAC (Digital To Analog Converter)
I build a digital to analog converter for the RC2014: [TODO: insert video here] Digital to analog converters are useful for interfacing microprocessors to analog devices. They typically take a digital value of a fixed number of bits (in our case 8 bits) and convert it to an analog voltage or current. The DAC presented …
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