You are 100% correct. The Heath Z80 boards & Trionyx Z8 will copy by HW the A7-A0 to A15-A8 to do as the 8080A does. Les’s Z80 board that I support do not do that. All the Z80 board that I support do follow the Z80 design.
On Heath Z80 board, U10 will copy U16 A7-A0 to A15-A8 lines. All done in HW.
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On Sep 7, 2021, at 11:46 PM, Terry Smedley <terry....@gmail.com> wrote:
I've been working on a TMS9918 prototype board, and decided to use the H8-7 breadboard (thanks, Dan!) to temporarily handle the bus interface and address decoding.
Glenn: Would you please post a few photos? How did he stabilize the insert?
From: se...@googlegroups.com [mailto:se...@googlegroups.com] On Behalf Of Glenn Roberts
Sent: Wednesday, September 08, 2021 5:49 AM
To: se...@googlegroups.com
Subject: Re: [sebhc] H8-7 Breadboard I/O address decoding
Thanks for the tutorial. I never understood this ‘til now.
The h-8-7 is a nice board. Last summer I did my “rescue” from Ed Aumiller in Virginia. He used to develop boards for the H8 by starting with a bare board (he bought them from Heath spare parts dept) and literally “hacking” the board - cutting out a rectangular shape to insert a wire wrap board, then using the decoding logic on the H-8-7 to interface to the bus. I have some of his leftovers from these experiments.
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Ahh, THX. They’re not coplanar; instead simply a big cutout for the field of WW pins and then attachment points at the overlapped edges.
How does that work with normal interboard-spacing? Does one have to leave the next slot open?
By my measurement there’s about ½” (~12mm) from the back of a board to the top of the chips on the board behind it. with the approach Ed used the wire wrap pins protrude about 1cm (10mm) behind the board so they would clear the top of the chips in the board behind, but if anything else was sticking up higher there would be an interference issue.
I’m talking the H8-Wire-wrap board and adding the point breadboard to avoid wire-wrap sockets as they are very expensive. It is in my To-Do-List. I think this makes more sense.
Norby
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