On Jun 2, 2021, at 1:23 AM, Mitchell Smith <kb3...@gmail.com> wrote:
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The beauty of this board is that it works with any H8 monitor and CPU’s (8080A, Z80). As I can select any memory region, it can be used to debug older memory boards. For example, I select the first 8K region for this board, skip another 8K region, and enabled the older memory boars above this region to debug it. Then I use the H8 front panel monitor to debug such older memory board.
This board works fine up to 10MHz.
Norberto
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Shadow Tron documented this 8080A/Z80 64K board in detail. He created 6 chapters which I enjoyed watching a lot. I need to add a link to my website.
https://www.youtube.com/watch?v=xpvd9NF3iq0 - chapter 1.
On this board the team rally behind it and it is well documented. I thank everyone that helped.
Norberto
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Great news! This board was designed to support the Heath Z80 and the Heath 8080A with any H8 monitors. Also it works with any other Non-Heath Z80 boards.
Which one do I use? Pin #18 or #24? And why? I decided to use pin#18 as it was Heath default to control the H17 floppy side sel signal. Heath gave the option to use pin#24 as well, but it was optional. The Z80 V4 uses pin#24 to send the IRQ signal to control better the I/O boards. It uses pin#18 by default to control H17 floppy side sel signal.
If the A16SW switch controls the second memory bank then what is this jumper for? You can add an external switch to toggle A16 manually. As it is battery backup to can use the upper 64K to store your own programs. Also if serves as a 64K spare region in case the first 64K goes bad for any reason.
J1, JP3 and JP4 work together.
JP1 – Install only when using NiCad rechargeable batteries. Do not install if using regular 2032 batteries
JP3 – Install jumper across pin 1-2 to select pin#18 on H8 bus as H17 side select (default).
JP4 – Install jumper or external switch to select either first 64K or second 64K. I usually install a jumper to store custom programs on the upper 64K region when using Heath CPU boards (memory test, front panel tests, H17 tests, etc.) I take out jumper to use the first 64KB region to boot HDOS or CP/M. Also it can be used as a spare 64K bank in case the first 64K bank goes bad.
JP5 – Install jumper across pin 1-2 when using Heath 8080A CPU. Note: The H8 “HA8-8 Extended Configuration” board must be removed. If using Z80’s with on-board Extended Configuration circuit, then a jumper must be added across pins 2-3 to disabled on board ORGSEL signal.
The maximum speed this board can do is 10MHz when using my Z80 boards. This board improves the reliability of the H8 system when using the 8080A board. Older memory boards have so many timing issues and it is a waste of time in fighting with them. I ran my H8 system for months non-stop while testing the CF storage solution and it never crashed.
Give me time on the H8 Extender as I need to improve its reliability. 😊
Thanks and have fun,
.
I forgot J1.
J1 – Is a copy of “P1” from the original Heath “HA8-8 Extended Configuration” board.
This is in case pin#18 and pin#24 are used for other functionality, so that you can add a wire from here directly to the H17 controller to control floppy side select.
Norberto
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I forgot J1.
J1 – Is a copy of “P1” from the original Heath “HA8-8 Extended Configuration” board.
This is in case pin#18 and pin#24 are used for other functionality, so that you can add a wire from here directly to the H17 controller to control floppy side select.
Sent: Wednesday, June 30, 2021 9:34 PM
To: se...@googlegroups.com
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On Oct 28, 2022, at 7:14 PM, norberto.collado koyado.com <norberto...@koyado.com> wrote:
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