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- Z80 home brew project
April 26, 2008, 4:46 pm
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I am working on a Z80 SBC home brew project and am looking for some
experienced persons who are interested in early testing and
development. Preferrably with electronic technician and/or engineer
with home brew SBC experience with your own tools and workbench.
The project is a Z80 SBC currently in transition from a prototype
board based system to a manufactured PCB. The previous version using
the prototype board worked OK on my bench so I am fairly confident in
the basic design. My plan is to move to a manufactured PCB to make
assembly and test much easier so I have redesigned the SBC.
Designed as a "new vintage" SBC it is made in the classic style: using
commonly available 100% through-hole DIP TTL chips (mostly 74LSxxx SSI
and MSI with a few common LSI), no programmable parts (PALs, GALs,
CPLDs, or FPGAs, etc) except for the EPROM. The intent is to make the
SBC easily assembled and tested with only basic tools (soldering iron
and VOM only -- Logic probe and oscilloscope are handy too).
The prototype board version has a monitor and CBIOS for booting CP/M
and supports a 32Kx8 EEPROM and 512Kx8 SRAM drive. The PCB version
has been modified to support a 1MBx8 EPROM drive instead of the 32Kx8
EEPROM. It includes basic 16550 UART, 8250 PPI, DS1302 RTC, and ECB
bus interface IO. The design attempts to keep the cost low but due to
several factors will probably cost around is estimated to be around
$100 for the parts.
If you are interested, please contact me offline. Thanks!
Re: Z80 home brew project
Well, OK, that is a $30 Z80 SBC but not a home brew computer. I think
you are missing the point.
Have a nice day.
I guess I did not realize you are building an entire computer.
Well, if I want to run CP/M all I have to do it go up into my attic and
bring down my Kaypro !!! <G>
BTW: The company I work for has some controls that were built back around
1982 that use the Z80.
The equipment is still in production... those things are still alive today !
It's not critical...but funny. When the "off" button is pushed, there is
about a 4 second delay to shut down.
Our newer controls with faster cpu's don't do that !
Re: Z80 home brew project
True, if all I wanted to do was run CP/M, I could run it on any number
of Z80 computers including a Kaypro. There are working CP/M computers
available on Ebay for $50 or often less. However, running CP/M is not
the point. This project is about building true home brew computers
which is *almost* a lost art these days.
I believe most people have not considered building their own computers
from scratch. There was a day not long ago when people would
regularly build their own computers at the component level (ie using
ICs and passive devices with soldered connections or using wire
wrap). Some even designed their own CPUs using just transistors and
While it is probably not realistic to build recent 32 or 64 bit
computers from scratch, the older 8 bit (Z80, 6502, 6809) and even
some 16 bit systems can still be practically done on a hobbyist
workbench using commonly available parts and tools.
That is what this project is about. It started as an empty prototype
board and some ideas. I would like to make it more available to other
people who are also interested in truly building their own home brew
computer from scratch.
I am not claiming this is unprecedented or some novel idea. There
have been numerous home brew computer projects in the past. P112 is a
great example as are many others. However, most projects assume a
high skill level and/or access to specialized equipment/parts. For
example, P112 includes schematics and PCB designs but relies on
difficult to obtain parts and also uses SMT components, neither of
which are readily available to many hobbyist builders.
Projects which only provide schematics leave it to the builder how to
actually create the board which I have found to be a critical design
consideration. Using breadboards, wire wrap techniques, and prototype
boards all have their strengths and weaknesses but none match the
benefits of a real manufactured PCB.