RC2014
http://rc2014.co.uk/

RC2014 is a simple 8 bit Z80 based modular computer originally built to run Microsoft BASIC. It is inspired by the home built computers of the late 70s and computer revolution of the early 80s. It is not a clone of anything specific, but there are suggestions of the ZX81, UK101, S100, Superboard II and Apple I in here. It nominally has 8K ROM, 32K RAM, runs at 7.3728MHz and communicates over serial at 115,200 baud.

RC2014 is available in kit form for you to solder together.  Through-hole components are used throughout, making soldering easy, even for those with limited soldering experience.  Along with a selection of modules to extend functionality, such as serial terminals with HDMI output, digital input modules or, simple keyboard, the RC2014 is a very adaptable computer.

Assembly guides can be found here:
http://rc2014.co.uk/assembly-guides/

Module information including schematic diagrams and technical descriptions can be found here:
http://rc2014.co.uk/modules/

GitHub repository can be found here:
https://github.com/RC2014Z80/RC2014

Google Group for RC2014 owners can be found here: