N8VEM ECB bus monitor and prototype boards
You are probably familiar already with the N8VEM Z80 CP/M home brew
computer project. There are a couple of updates you might be
Recently some builders on the N8VEM project got the ECB bus monitor
board working. Builders can use it to debug hardware and software
using the ECB. It is based on a ECB bus monitor originally from the
C'T Projekt magazine published in 1985 but updated for the N8VEM
project to address parts obsolescence and some extensions.
The ECB bus monitor is conceptually similiar to the Jade Bus Probe for
S-100 but for ECB. It allows for LED bus monitoring, address bus
trapping, single stepping mode, and other features described in the
article. There are some videos of the ECB bus monitor available on
From my friend Rolf:
From my friend Clive:
The original article mentions the ECB bus monitor can be adapted to
use with the Z80 directly via a custom socket adapter but I have not
tried it myself. There is an English translation of the article
available on the N8VEM Google Group. The PCBs are available for $20
plus shipping. Caution: the article is in German and 29 MB.
In addition, I am finishing an N8VEM prototype board which will be
going to manufacturing soon. Its purpose is to allow builders to
easily make their own custom ECB peripherals by providing a common
platform and interface. It provides for a 160x100 Eurocard with DIN
41612 bus connector (not included), ECB bus signal export pads, full
buffering of address, data, and incoming control bus signals.
Commonly used signals are exported to a fully labeled set of pads for
easy builder access in custom circuitry.
Programmable partial IO address decoding (high nibble only) which can
be extended with custom logic. There is an area with grid plated
through hole for builder circuitry. VCC and GND rails for short
connections to ICs. More information is available on the N8VEM Google
Group. When I receive the PCBs from manufacturing they will be
available for $20 plus shipping.
If you are new to home brew computing, some highly motivated builders
have produced excellent introductory webpages on how to get started.
James excellent work here at Instructables:
Oscar has written this wonderful introductory piece:
In addition, there have been numerous builder projects adding all
sorts of various IO devices, new and modified software, etc.
I have PCBs available for the SBC, the ECB backplane, and the ECB bus
monitor. They are $20 each plus shipping. Shipping is typically $2
each in the US and $5 overseas. Multiple boards per order reduces per
unit shipping costs but has to be determined depending on weight.
If you have any questions about the N8VEM Z80 CP/M home brew computer
project please send me an email or join us on the N8VEM Google Group.
Please note this is a completely voluntary amateur noncommercial
"open" project. All hardware and software information is available on
Thanks and have a nice day!