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

[Zippster]

I have an Elenco LP-560 logic probe that works well and
has a switch to choose between TTL and CMOS levels.
They are pretty cheap, a little over $20 shipped.

<http://www.amazon.com/Elenco-Electronics-LP-560-Logic-Probe/dp/B000Z9HAP4 <http://www.amazon.com/Elenco-Electronics-LP-560-Logic-Probe/dp/B000Z9HAP4>>

For an Oscilloscope, I bought a Hantek DSO5202B from these guys on eBay.
Works very well.  Pretty much a must have if you start working with analog signals.

<http://www.ebay.com/itm/HANTEK-200MHz-Digital-Storage-Oscilloscope-DSO5202B-/221584092234?pt=LH_DefaultDomain_0&hash=item339770ec4a <http://www.ebay.com/itm/HANTEK-200MHz-Digital-Storage-Oscilloscope-DSO5202B-/221584092234?pt=LH_DefaultDomain_0&hash=item339770ec4a>>

For pulling chips I use a fairly wide (about the width of a .300 dip package) flat-bladed screwdriver with 
the tip filed down to a thin, chisel-like point.  Makes it very easy to slide under chips and pry them
up first from one end, and then the other, alternating so as not to bend pins.
The purpose made chip pullers I’ve seen are cheap and probably more likely to damage a chip,
especially if it is very tight in the socket.  I always use the screwdriver on dip packages.  
PLCC use a puller though.

A modern PC with an DB9 serial port should support flow control signals, and your
box may well be expecting them.  I didn’t see anything but baud rate mentioned in my very quick
look at the manual in the link, but that doesn’t mean much.

I haven’t used any serial port diagnostic software before, so I can’t recommend any.
I have done the “try every possible combination of baud rate and flow control” though.
Since there was a schematic in the link you had, you should be able to determine/verify 
the proper pins on the connector (tracing them back to the UART if necessary).

CP/M is actually a pretty cool OS.  Well documented and easy to program for.
The lack of graphics would be the down side.  For computers using serial communications
it’s great.

- Ed


> On Mar 16, 2015, at 6:18 PM, Christopher Barnett Fox  wrote:
> 
> Thanks, Ed!
> 
> A reason to buy a logic probe and/or oscilloscope?! OK! Sold. I'd
> appreciate some recommendations.
> 
> I had the cover off the unit over the last couple of days, and sealed it
> back up last night. If I recall correctly, though, most if not all of the
> ICs are socketed. However, I have a crap chip puller. Recommendations
> there would be welcome, too.
> 
> Initially, I was trying with an old Kensington USB to Serial converter on
> a Mac. But, I ended up trying on a Tandy Model 102, which as a proper
> (although limited?) DB25 serial port. Still no satisfaction. However,
> IIRC, the Tandy Model Ts don't support hardware flow control of any kind?
> I think this SBC might be expecting a signal like DTR or CTS? I don't know
> that the Model 102 serial port supports those lines.
> 
> I have access to relatively modern PCs that have DB9 serial ports. Will
> those carry all the relevant signals? What about modern serial diagnostics
> software, that could at least identify what lines were high/active? Any OS
> is fine, if you have some serial diagnostic applications to recommend.
> 
> Thanks for your help, Ed. I'd been wanting to play with CP/M, and picked
> up this little box cheap off eBay about a year ago, and I'm only just
> getting around to trying it out.
> 
> Christopher
> 
>