[Intel-devsys] Tauntek/Grieb Z80 and 8080 ICEs
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?
[I have a comment, at the end of Jon's post. - Herb]
Re: Tauntek/Grieb Z80 and 8080 ICEs
[from - Jon Bradbury]
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:
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
I also designed a layout using SMD ICs, which may be even easier to
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
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.
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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