[Coco] Multicomp Microcomputer Madness!

[Kip Koon]

Hi Hardware and Software Enthusiasts!

I've also noticed very little activity on the Coco List over the last few
days so I thought I'd put out an email to see if it goes through and share a
little bit about my activities with Grant Searle's Multicomp Microcomputer
at the same time.  

I have successfully compiled, programmed and played with all three versions
of the Multicomp each with their associated Basics in Rom - the 6809, Z80,
and 6502 Multicomp designs in their entirety.   They all work great, but
what about storing files on the SD Memory Card?  As these designs are
probably proof of concept designs, none of them have any software driving
the online storage yet so I began to look for folks who were working with
the Multicomp and see what popped up on the horizon.  

I noticed a flurry of activity on the N8VEM list talking about getting CP/M
2.2 running on the Z80 Multicomp with an interface PCB that integrated all
the features and capabilities of Grant Searle's design!  The Interface PCB
also upgraded the 128KB Static Memory chip to a 512KB static ram chip.
Really!?!  That reminds me of another 6809 based computer.  :)  

I had gotten interested in CP/M very early in my computer life, but with the
hardware being so prohibitively expensive and I in my early 20s, I relegated
myself to finding something else.  That's when I got into the Coco.  Well,
spin the time machine forward about 35 years and I'm looking at plugging the
Altera FPGA Mini-Development PCB into an Interface PCB with 512KB of Static
ram, two serial ports, a VGA Color Video output port, a PS/2 Keyboard input
port, a Monochrome Composite Video Output port and an SD card interface.
And there is also a 40-pin male header for a color TFT LCD touchscreen as
well which one of the guys on the N8VEM list has running under CP/M 2.2!  

Over a period of several weeks to a month or so I began to collect all the
parts I needed to build the first version of the Interface PCB.  Now I have
three versions of this PCB built and I must say I am very impressed indeed!
The only Disk Operating Systems that have been ported to this Multicomp
Microcomputer are CP/M 2.2, CP/M 3.0 and MP/M II 2.1 for the Z80 Multicomp
and the Cubix OS for the 6809 Multicomp.  I have not heard of any Flex9
activity nor of OS-9/NitrOS-9 being ported over yet either.  There included
in the VHDL source code is a fourth cpu, the 6800 CPU, so Grant will be
releasing a 6800 Multicomp design at some point in the future!  Grant says
he already has the 6800 Multicomp running successfully, so I'm eager to play
with that version as well as soon as he publishes the files to his web site.
Now how about Flex2?  :)  Would you believe I have heard of someone running
OS-9 on the 6800!  Believe it or not!

Well, since there is so much activity on N8VEM about the three flavors of
CP/M, I decided to dive in and take part.  To make a long story very short,
I now have a Z80 Multicomp running CP/M 2.2, CP/M 3.0 and MP/M II 2.1 all
booting from the same SD card along with a FAT16 partition to easily move
files from my laptop to my Multicomp!  In addition, there is an Interrupt
Controller and a Memory Management Unit both fully functional as well.  The
Z80 Basic CP/M rom gets swapped out before CP/M or MP/M are booted so CP/M
has a full 64KB to work with plus a ram disk and MP/M uses an even larger
portion of the 512KBs of ram.  There are $6900 bytes currently dedicated to
the MP/M II system programs and three 48KB Transient Program areas for up to
two users to work with as well.  It even has an LED activity light to show
when the SD card is being accessed.

This Z80 Multicomp Microcomputer is absolutely fantastic. This Triple Threat
Z80 Multicomp Microcomputer as I like to call it, is quite a powerful little
computer.  Oh yeah, one more thing, this rascal runs at a blazing 25MHZ!  

 A month or so ago I had no knowledge of any of those three OSes nor of
FPGAs, now I know a little about them all and I'm having a lot of fun
learning even more.  I've got plenty of manuals to read too.  More
importantly, I have realized a dream that has been a long time coming!  Now
I can play with CP/M and MP/M on my own hardware!  In fact this hardware is
so small compared to the original Altair and IMSAI microcomputers that
initially ran CP/M and MP/M that I can hold the entire Multicomp
Microcomputer in the palm of my hand!  I can't get over how tiny this thing
is compared to the original!

Once I settled down from my enthusiasm, I realized I still needed an OS for
the 6809 Multicomp.  Well, one day I saw an email on the N8VEM list about
running 6809 Cubix on the 6809 Multicomp.  I had known about Cubix for some
time, but had nothing to run it on except in an emulator on my laptop.  I
wanted more so I downloaded the 6809 Cubix files from the N8VEM web site and
began working on getting Cubix operational.  I've got everything compiled
and programmed into my 6809 Multicomp using a second FPGA Mini-Development
PCB, but it's not functional yet, so something is amiss, therefore I'm
currently troubleshooting why Cubix is not booting.  I'll get this working
too.  Well that pretty much sums up my recent activities all densely packed
into a tiny nut shell.  :)  Thanks for reading!  Take care my friends.

 

Kip Koon

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