[Coco] CDP M64 Z80A CP/M machine, was Re: cordinated coco conference

[Zippster]

Hi Christopher,

It could really be anything at this point, you don’t really know what is working
or not yet, correct?

I assume this machine has been sitting a long time.  Not familiar with this
system, and can’t really read all the chip #’s, but….

Do you have a logic probe or oscilloscope?

I guess I would start with pulling and resocketing all the socketed chips to make sure
there is decent contact.  Then make sure the Z80 is getting a clock signal, and work
out from there. Verify activity between the CPU and system ROM, and that there is
some kind of output on whatever is feeding the serial port (at startup).

It should show some output on the expected lines at the serial port at startup if that is 
it’s default communications setup.  If so, you could connect the terminal port to a RS232
port on a pc, using a terminal program, then switch through various com settings (on the PC)
trying to get something on the screen (while restarting the machine each time).
Try various flow control settings, etc.

I would use a real serial port and not a usb to serial cable for this, as it can throw
it’s own issues into the mix and make it more difficult. 

Wow, just noticed you even have the schematics and rom source on that link.
Looks like plenty of documentation.  Very nice.  Runs CP/M too?  Nice computer.

- Ed



> On Mar 16, 2015, at 1:15 PM, Christopher Barnett Fox  wrote:
> 
> Group,
> 
> I realize this is a tangent and not directly related to the CoCo, but
> since we're talking about SBCs, other CPUs and operating systems, I
> thought I might take advantage of the collective knowledge here.
> 
> I've recently become the owner of a vintage 1984 Columbia Data Products
> "Commander M64", a Z80-based CP/M machine. This one was used as part of a
> Kodak Ektalog system. I'm having some trouble getting it working ;
> specifically, it won't seem to talk to a serial terminal emulator.
> 
> Here's a web site I found about this SBC:
> 
> http://www.aximel.com/m64/index.html
> 
> The unit gets power, as the fan and disk drive motor spin. I think I've
> got the serial parameters matching, e.g. 19.2Kbps, 7 word bits, even
> parity, 1 stop bit, but no satisfaction.
> 
> Any hints or tips?
> 
> Thanks!
> 
> Christopher
>