32K ROM?

[smb...@gmail.com]

I've noticed that the Z80 boards have an option to support 32K ROM address space instead of 8K... I was curious what this is used for -- do we have 32K ROM images, and if so what is present in the extra space?

Thanks,

Scott

[norberto.collado koyado.com]

Only the following boards will support the 32KB Monitor. As it is an EEPROM, we can download the FW thru the VDIP1 module.

 

1. Z80 V4.x
2. Z180 V5.x
3. 8080A V1.x

 

It is described here: http://sebhc.durgadas.com/mms89/h8mon2/H8-Monitor-2.pdf

 

Douglas can give you more info if needed.

 

Norberto

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[smb...@gmail.com]

Thanks Norberto, that is quite a nice feature set.

Scott

[norberto.collado koyado.com]

These are the extended COMMANDS menu on the H8 8080A board. You do not need to use the H8 Front Panel as everything can be done thru the serial port as in the H89.

 

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[Glenn Roberts]

The Z80 board can also be run as a single board computer. I’m guessing that will be true of the 8080 and Z180 boards as well? And the new backplane has an ability to be electrically split in half, so you could have two independent cpu boards in the same chassis - one using the front panel and one in SBC mode…

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On Jan 23, 2023, at 2:37 AM, norberto.collado koyado.com <norberto...@koyado.com> wrote:



These are the extended COMMANDS menu on the H8 8080A board. You do not need to use the H8 Front Panel as everything can be done thru the serial port as in the H89.

 

To view this discussion on the web visit https://groups.google.com/d/msgid/sebhc/SN6PR01MB3855C8DF124E9E809875DD71F7C89%40SN6PR01MB3855.prod.exchangelabs.com.

[Douglas Miller]

For the Z80 and Z180, I build a "n" (no FP) version of the ROMs, so you can use that in the case where the CPU is run without the FP.  For some reason, I had concluded that the 8080A board could not run without the FP.  But, in theory, the same thing could be done.

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[Douglas Miller]

I remembered why I did not build a "no FP" version of the 8080A EEPROM. The 8080A board has no independent 2mS clock (or single-step control), so I assumed it could not run without the FP.

[norberto.collado koyado.com]

Do I need to add the H89 interrupt circuit to the 8080 board? We still have space in the prototype area.

 

Norberto

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[Douglas Miller]

I didn't see any 2mS clock on the 8080A schematic. Is there one? The "2mS clock enable" bit on port 362Q was not connected.

If there's no 2mS clock on the CPU board, we don't need port 363Q.

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[norberto.collado koyado.com]

I will need to add such circuit as well. About three IC’s.

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[Douglas Miller]

So you did intend to make this board work without the front panel?

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[norberto.collado koyado.com]

My intent was to stay as the original board. That is why the H37 interrupts were missing. That was easy fix. I do think, we do not need them as the 8080A will connect to the front panel and the Z80/180 can be run without the front panel in a 2x CPU configuration.

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From: se...@googlegroups.com <se...@googlegroups.com> on behalf of Douglas Miller <durga...@gmail.com>

Sent: Monday, January 23, 2023 4:41:30 PM

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[smb...@gmail.com]

Norberto, I wanted to ask more about the "avoid double 2ms counter interrupt" circuit above. Assuming the jumper is on positions 2-3, is the assumption that either the front panel is generating !INT1 or this circuit is generating !INT1, but not both at the same time? This is assuming an original front panel is used, not the new one that can utilize its own clock.

Scott

[norberto.collado koyado.com]

The H89 interrupt circuit was added to the board to make it behave as an H89 inside the H8 chassis and to boot MMS CP/M3 as the H89 did. CP/M3 was only supported on the H89 and not the H8 system. During initial tests it was found that the H8 was getting double interrupts, one from the front panel and one from the H89 circuit causing issues to the OS. To avoid the doble interrupt a flipflop, a gate, and a jumper was added when using the front panel.

 

Jumper position 2-3 = H8 front panel is generating the Interrupt or H89 is generating the interrupt under software control on port 363Q to boot MMS CP/M3. (NOT BOTH)

Jumper position 1-2 = H89 is generating the interrupt all the time as it is controlled by the HW on port 362Q.

 

In other words is like copying the H8 front panel interrupt circuit onto the CPU board, so that we can run the board without the front panel.

 

The circuit works fine with the old front panel or the new front panel.

 

Here is the second part of the circuit to understand better how this works.

 

 

From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of smb...@gmail.com
Sent: Monday, January 23, 2023 10:29 PM
To: SEBHC <se...@googlegroups.com>
Subject: Re: [sebhc] 32K ROM?

 

Norberto, I wanted to ask more about the "avoid double 2ms counter interrupt" circuit above. Assuming the jumper is on positions 2-3, is the assumption that either the front panel is generating !INT1 or this circuit is generating !INT1, but not both at the same time? This is assuming an original front panel is used, not the new one that can utilize its own clock.

 

Scott

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