[Intel-devsys] Tauntek/Grieb Z80 and 8080 ICEs

Herb Johnson hjohnson at retrotechnology.com
Thu Aug 8 08:56:24 MDT 2019


Jon Bradbury asks Herb Johnson, Thu, 8 Aug 2019 12:26:14 +0100:

Hello Herb: I’ve been trying to post this message (below) to the 
intel-dev group but the messages are being bounced. I wonder, could you 
post it on my behalf, please?

Thanks, JonB

[I have a comment, at the end of Jon's post. - Herb]

-------------

Re: Tauntek/Grieb Z80 and 8080 ICEs
[from - Jon Bradbury]

Hi team

I have only skimmed this discussion but I would like you to know that I 
successfully replicated Bob Grieb’s 8080 ICE using a 3.3v XC9536, which 
IS easy to get hold of. Here it is debugging an MDS 230 IPB:

https://drive.google.com/open?id=1TNeZ5SluoiMPsPiP-BlqsD-vQUzV6W2P

It is a completely different layout to Bob’s board because I had to add 
extra circuitry to support the 3.3v part and I needed to keep the board 
as small as possible. This 3D render may give an impression of what it 
looks like:

https://drive.google.com/open?id=1fesP1e3hXXftXP_4bdlN0fI-jCbjVWOf

I also designed a layout using SMD ICs, which may be even easier to 
source: https://drive.google.com
/open?id=1eR_srC_amgDagXEGf8G5H46_flbIWJRE

So. It appears to work (as the first picture shows) except that it has 
difficulty reading the MDS IPB RAM reliably. However, I do have one of 
Bob Grieb’s original boards and this exhibits the same problem; thus, I 
concluded the issue is caused by some anomaly of the MDS timing that the 
ICE is not catering for. Perhaps someone on the group could verify this 
hypothesis. There’s another problem with my board and that is the RS232 
header is not wired correctly. Signals are there but not on the right 
pins, so you can’t plug a PC DB9 flying lead directly onto it as I had 
intended... dagnammit!

I have a stack of 8080-ICE boards here but they are quite expensive to 
build (in terms of parts cost and time). So they would not be 
particularly cheap (I need to recoup the development costs). If you are 
interested, please form an orderly queue...

The 3.3v CPLD approach will obviously work for Bob’s Z80-ICE as well. I 
just haven’t got round to capturing the schematic and laying it out yet.

Note: I did get Bob’s permission to do this, and copies of all 8080-ICE 
IP – but I would need to ask for the Z80-ICE IP to reproduce it.

One more point – a member of the retrobrew community – maybe Gary – did 
succeed in securing a number of 5v CPLDs from LoTech in the UK. I had a 
chat with him and as he was going to build more ICE boards I kind of 
shelved my production until all his were sold.

Regards

JonB

P.S. Credit goes to my friend John Hales for double checking my 8080-ICE 
schematic capture and loaning me his own Tauntek 8080-ICE for testing, 
as well as some other equipment. Cheers!

------------------

[From Herb: Jon Bradbury, I suggest you include a Google Drive link, 
that spells out (a human visual text description) which Google Drive and 
folders your links are pointing to. Otherwise these are "blind" links 
only usable to persons who happen to have permissions for whatever 
G-drive these are on. [I got access.] There's other reasons, such as 
"five years from now, these blind links might fail". It's up to you of 
course. - herb]



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