The BQ4845 RTC

The simplest external device I could see for my first attempt at a peripheral was the TI BQ4845 RTC. It's a DIP package and works like an SRAM, can have a 32,768Hz crystal attached directly to it, and has a simple interface for connecting and programming.

An expansion header board for the CPUville kit

With the C compiler working it was time to get back to the hardware and make it possible to experiment with new devices.

stdio functions via the CPUville monitor

This post covers replacing the standard crt0.rel file and making stdio work with the CPUville monitor.

Using SDCC with the CPUville system

As much fun as assembly coding is, sometimes (most times) I want to be lazy and use C.

SDCC knows how to emit Z80 code so that looked like a good place to start. It is easy to download and install and until you start trying to tell the linker how to lay memory out it is pretty easy to use too.

A review of the CPUville Z80 computer kit

I was introduced to computers in era of the C64, so the nostalgia is strong for 8-bits. I love the way you can understand them and programming them is fun in a sort of 'real programming' sense where you don't feel so isolated from the hardware. I don't get any of that from modern computers, no matter how cool the hardware. I'm just not smart enough to do OpenCL programming, or even shaders.

So about a year ago I tried to design my own minimal Z80 based system but could never get it to work beyond free running NOPs on a bread board. I gave up on it but then made the mistake of looking at EEVblog and Hackaday again recently and now I'm back having another go.