Dual CF Firmware Instructions

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glenn.f...@gmail.com

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Jul 7, 2025, 9:18:58 PMJul 7
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I’ve been working with Mike Cassidy to flesh out the assembly instructions for the H8 Dual CF board. One thing I can’t find well documented anywhere is the firmware that needs to be loaded into the ROM and where to get it.  I’ve written up some detailed instructions on the Heath 8080 board and how to use the EEPROM adapter but I’m struggling to understand what’s needed for some of the other architectures, especially the wide range of Z80 boards. I’ve got a table partially populated (below) but could use some help.

 

e.g. on the Rev 3.x board we don’t seem to have a firmware available with the CF boot code installed at 020.000 ??  I could probably create that if it’s not already somewhere…

 

on the Rev 4 board I think Douglas has developed a firmware that includes a direct boot command??  Where?? Which one? Is there also something equivalent for the SEBHC 8080A board and the Z180??

 

Systems that just have XCON8 can do “single key” booting because key 3 was not being used so Rick added the appropriate jump there (in the XCON8 code), but Z80 boards with PAM-37 don’t have a similar feature (PAM-37 uses a very different approach to quick booting) so they must use the full multi-key boot sequence from the front panel (right?)

 

Thanks for any input/guidance on this…

 

  • Glenn

 

 

 

Dual CF Firmware/Boot Options

Source

CPU Board

Image

Boot Procedure

Notes

Heath

8080

Use EEPROM Adapter w/ 8K image "8080A_XCON8_Monitor" from Norberto "new" web site

Single key "3" from front panel

See instructions for board mod's

Heath

Z80 (HA8-6) with XCON8 or PAM37 ROM in U13

Program 2532 EPROM with "Heathkit_Z80_444-70_Monitor" and install in U19

22-key sequence

Heath Z80 ROM sockets wired for 25-series ROM

SEBHC

Z80 (Rev. 2.6) with PAM37+ ROM (2732) in U4

Program 2732 EPROM with "Heathkit_Z80_444-70_Monitor" and install in U3

22-key sequence

SEBHC Z80 ROM sockets wired for 27-series ROM

SEBHC

Z80 (Rev. 3.x)

SEBHC

Z80 (Rev. 4.x)

SEBHC

8080A (Rev. 1.0)

SEBHC

Z180 (Rev. 5)

22-key Boot Sequence: MEM 0 0 0 3 6 2 OUT REG PC ALTER 0 2 0 0 0 0 ALTER GO 1 0 #

 

Joseph Travis

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Jul 14, 2025, 9:54:11 PMJul 14
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I regret that I didn't respond to this email previously but to be honest, I have nothing to add to this.  When Rick and I first embarked on this endeavor, I had two 8080 CPU boards (one with the Pat Swayne Z80 mod) and Norberto's H8-Z80-64 CPU/GIDE Rev 2.6 board.  I think Rick also had an 8080 CPU board and a Trionyx Z80 CPU board.  Those were all we had to test with.

The 28C256 adapter board was the result of an idea I had prior to the DCF board to enable larger 28p ROMs to be used in the 24p socket.  It worked out well for the DCF development and test.  I also used it briefly for the H89-CF development.

It seems each Z80 CPU board has its own peculiarities which may require some "finessing" but the idea is still the same.

Thank you Glenn and Mike for your efforts -  it's greatly appreciated!

Joe


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glenn.f...@gmail.com

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Jul 15, 2025, 6:53:50 AMJul 15
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Thanks Joe. You and Rick did great work here and the Dual CF provides a nice solution for many users.  I think I’ve mostly figured out the main Z80 configurations and Mike and I are working on finishing our writeup. Hopefully useful for those who want to build out one of these boards….

 

  • Glenn
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