SC129 is a digital I/O module designed for the RC2014 bus.

In part 1 of this series we took a very quick tour through the whole process of designing a product. In part 2 and part 3 we designed the electronics for a digital I/O module. We will now design the circuit board.

In part 2 of this series we started designing the electronics for our digital I/O interface. In this part we will complete the schematic.

In part 1 of this series we took a very quick tour through the whole process of designing a product. We will now begin a much more detailed look at designing a Digital Input/Output interface for a Z80 computer.

Someone recently asked me a few questions about design, which got me thinking about writing a series of posts for this website.

I hope to encourage anyone who has considered designing their own retro computer add-on, or indeed a whole system, to have a go. Getting that first professional looking PCB in the post is very rewarding and is relatively cheap.

SC126 Z180 SBC / Motherboard with RomWBW firmware has now been released.

Currently in development is a Z180 motherboard with RC2014 compatible expansion sockets.