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Z-80 I/O

Z-80 Homebrew: I/O board!

The next step on my Z-80 journey is building the I/O. I decided to do this before building the processor circuit itself as it doubles up as a handy test device. There are three output ports that use TIL311 displays; I got these cheap off eBay from Hong Kong. They take a four-bit input and display it as a hexadecimal value. Therefore, in pairs, they can display binary data from the data bus as a hexadecimal number 00h – FFh. They aren’t all connected to the data bus; I’ve kept them separate, so if necessary I can connect them to…

Z-80 Homebrew – First Update

I’ve always wanted to build my own computer from the circuit up; so inspired by Steve Ciarcia’s Build Your Own Z-80 Computer and my success building a computer from CMOS Logic I thought it was time to have a go! Most of the components are no longer available, but the Z-80 CPU itself is still in production. So with a bit of re-designing it should be easy to build a computer following Ciarcia’s design. First up: the power supply. It’s a simple design based around a 7805 regulator that takes a 9V supply from an old transformer and reduces it…

CMOS Logic Computer

8-bit CMOS Logic Computer

This is my 8-bit computer built from CMOS logic gates, based on the SAP-1 in Albert Paul Malvino’s Digital Computer Electronics. It was hard to avoid creating a rats’ nest of wires, but there is (surprisingly) about 40m of wire in total. Its hard to gauge the amount of detail to describe this project in; there’s enough for a whole book’s worth describing it from the logic gates up, so I’ve provided a brief overview and a video that shows how it works in action! The computer is fully programmable and it can add and subtract numbers from 0 to 255. The computer…

‘Reappraising the Seicento’ Available Now

It is now possible to place an order for my book ‘Reappraising the Seicento: Composition, Dissemination, Asslimilation’ of which I am both a joint editor and contributor. Reappraising the seicento presents new perspectives on some relatively well-researched areas of music history and adumbrates some more arcane aspects of the period, offered by fledgling scholars and early career researchers in the field of musicology. The scope of the title has the potential to warrant a tome on the subject, but it is not the intention to provide a comprehensive survey of music in the seventeenth century. Instead, five essays are presented,…