January 21, 2019
This is the Z80 CPU module I demonstrated a few months ago. It is designed to work with the RC2014 bus.
So what makes it special? Well, the module includes a number of extra features and enhancements designed to simplify a system build. These include:
It will work with either the standard RC2014 bus or the latest enhanced bus where all the Z80 CPU signals are available.
It includes several options for generating a signal clock: Crystal, Oscillator or taken from RC2014 back plane.
A reset circuit is included.
And the signals INT, NMI, BUSRQ and WAIT feature 10K pull-up resistors.
The schematic is here:
and you can find it on Tindie here:
January 28, 2018
I’ve been busy with my big box of PCBs and I here’s my first Z80 system design and build. It comprises of the following:
– Z80 CPU card
– 8K ROM & 8K SRAM card
– 68B50 ACIA card
– 5-slot enhanced+ backplane
It’s pretty much a standard Z80 layout but I’ve expanded the bus to the latest Enhanced Bus definition for all the cards. The 5-slot backplane uses double row (2×39) female pin headers to include the RC2014 enhanced bus and in addition I’ve added an extra set of address lines (A16 to A23) for the possibility of using 16-bit CPU’s (8086/68000) and memory options (upto 1MB) in the future.
Here’s some pics of the various cards:
ACIA UART Card
November 29, 2017
I have very fond memories of using and building 8-bit computers during the 1980’s, so I’ve been following Spencer Owen’s RC2014 modular 8-bit computer project with some interest. For those interest the RC2104 is a simple but very modular 8-bit microcomputer based around the Z80 microprocessor.
In its most basic form it uses a number of single row 40-pin headers (or sometimes a 39-pin header) to make a computer backplane and which takes various “computer” and add-on cards to build a system. The add-on cards currently have a choice from various Z80 CPU cards, a 6502 CPU, various sizes of RAM and ROM memory cards, serial I/O and digital I/O cards.
I was fortunate to meet Spencer at Maker Faire UK back in April 2017 and chat with him first hand about the RC2014 project and he was very open and enthusiastic about sharing all aspects of his project. So much so, a small community of fellow builders has popped up and added to the project with their own add-on cards.
I’ve put together a short list of RX2014 related web-sites:
http://www.ndr-nkc.de/compo/index.htm //very similar system from 1980’s