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Month: October 2014

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…