H89-DCF...

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Joe Travis N6YPC

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Jan 18, 2023, 1:08:52 PM1/18/23
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I was so inspired by Rick Davis' design and work on the H8 Dual CF board that I decided to duplicate it for the H89.  It uses just 4 ICs, 4 diodes, 4 resistors, 2 40p IDC connectors.

I already know the haters are gonna poo-poo the use of 8255s but I feel there is beauty in simplicity.  Besides, I'm unaware of anyone pushing their H89s beyond 4 MHz.

Now I'm hoping the design will be picked up and boards created for the H89.

Joe
20230118_115555.jpg20230118_112209.jpg

Dave McGuire

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Jan 18, 2023, 1:28:18 PM1/18/23
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On 1/18/23 13:08, Joe Travis N6YPC wrote:
> I was so inspired by Rick Davis' design and work on the H8 Dual CF board
> that I decided to duplicate it for the H89.  It uses just 4 ICs, 4
> diodes, 4 resistors, 2 40p IDC connectors.

Very cool.

> I already know the haters are gonna poo-poo the use of 8255s but I feel
> there is beauty in simplicity.

Your pointed comment was received loud and clear. I'm not a "hater";
I'm a commercial design engineer who focuses on good engineering
practice and the simplest solutions possible because that's how I make a
living. Sticking a fairly complex chip in there where it absolutely
isn't required is not "simplicity", it's just the opposite.

That said, I respect and applaud your efforts anyway, and if PCBs are
made available for your design, I will buy three or four for my machines
and those at the museum.

-Dave

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Terry Gulczynski

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Jan 18, 2023, 1:31:38 PM1/18/23
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Joe,

Re: your comment about H89s over 4MHz...

I have 2 H89's running @ 12MHz and one at 8MHz. I sold a fourth one a
couple years ago that also ran at 12MHz. All four machines include a
double IDE port design based on the original GIDE by Tilmann Reh, along
with 1MB of Static RAM.

ANY design is welcome to me - 8255 works just fine.


Terry

On 1/18/2023 1:08 PM, Joe Travis N6YPC wrote:
> I was so inspired by Rick Davis' design and work on the H8 Dual CF board
> that I decided to duplicate it for the H89.  It uses just 4 ICs, 4
> diodes, 4 resistors, 2 40p IDC connectors.
>
> I already know the haters are gonna poo-poo the use of 8255s but I feel
> there is beauty in simplicity.  Besides, I'm unaware of anyone pushing
> their H89s beyond 4 MHz.
>
> Now I'm hoping the design will be picked up and boards created for the H89.
>
> Joe
> 20230118_115555.jpg20230118_112209.jpg
>
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Joseph Travis

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Jan 18, 2023, 2:00:46 PM1/18/23
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Dave and Terry,

'My apologies. I didn't intend on my comment being received as harsh as it appears to have been. No offense intended.

In this case, I view the simplicity as fewer number of ICs.  It would likely double the number of ICs needed by not using the 8255s.

Terry, I think it is awesome that you are pushing the limits of the H89!  I wonder how many others are doing this and just what it takes.

Thank you both!

Regards,
Joe Travis n6ypc


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Dave McGuire

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Jan 18, 2023, 2:02:57 PM1/18/23
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On 1/18/23 14:00, Joseph Travis wrote:
> Dave and Terry,
>
> 'My apologies. I didn't intend on my comment being received as harsh as
> it appears to have been. No offense intended.

No worries.

> In this case, I view the simplicity as fewer number of ICs.  It would
> likely double the number of ICs needed by not using the 8255s.

Actually not. The CF spec requires CF cards to implement 8-bit mode.
When in that mode, the CF interface is nearly identical to the
processor's bus. (because it was for the 8088's bus) All you need is
some address decoding.

norberto.collado koyado.com

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Jan 18, 2023, 2:53:36 PM1/18/23
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Very nice Joe and it looks beautiful. I can help with the layout but using the high-speed CF design that connects directly to the H89 bus once we get it running under HDOS and CP/M. The 82C55 should be fine up to 8MHz and if we add one I/O wait state it would work up to 16MHZ.
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Subject: Re: [sebhc] H89-DCF...
 
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rw...@robhome.com

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Jan 18, 2023, 2:53:39 PM1/18/23
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Are there drive size limitations on the GIDE drives? I ask because I'm wondering if we could use an IDE to SATA converter to use larger SATA drives.

Rob Waggoner
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Joseph Travis

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Jan 18, 2023, 3:06:35 PM1/18/23
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I'm not sure what purpose that would serve.  Due to the limitations of HDOS and CP/M, you reach a point of diminishing returns once you go beyond 16MB.


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norberto.collado koyado.com

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Jan 18, 2023, 3:17:53 PM1/18/23
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When using the 82C55 you can drive SATA drives with the SATA to IDE adapter. This works on the Z67-IDE+. It is easier to use the CF or SD card. You can use an SD to IDE adapter. Only one SD card is supported by the Z67-IDE+ controller.
From: se...@googlegroups.com <se...@googlegroups.com> on behalf of Joseph Travis <jtravi...@gmail.com>
Sent: Wednesday, January 18, 2023 12:06:21 PM
To: se...@googlegroups.com <se...@googlegroups.com>
Subject: Re: [sebhc] H89-DCF...
 

Joseph Travis

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Jan 18, 2023, 6:01:37 PM1/18/23
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Thank you Norberto! It would be nice to show the H89 some love!

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norberto.collado koyado.com

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Jan 18, 2023, 6:56:50 PM1/18/23
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No problem. I will help you with the board layout. Do you have some handmade schematics that you could share or just use same schematic for Ricks board adapted to the H89?
Sent: Wednesday, January 18, 2023 3:01:22 PM

glenn.f...@gmail.com

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Jan 18, 2023, 8:25:31 PM1/18/23
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Agree. Even the 8 and 16G (heck even 2G) CF cards are more than enough.  Norberto has added thumb switches to the Z67-IDE+ to select different segments of the drive, so that you can set up different system configurations.  This is a clever capability (but frankly in 10 years I’ve never needed it or used it – your mileage may vary)…

Douglas Miller

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Jan 18, 2023, 8:34:18 PM1/18/23
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I've also added the option to CF (and SDCard) boot to select a 256M "segment" to boot from. However, the OS must honor that selection and use it as an offset to all disk I/O. CP/M 3 and MP/M honor it, and we'll have to try and get Heath CP/M and HDOS to also use it.

But, as Glenn said, I haven't used it other than for testing the feature. Mostly just leave vast areas of the disk unused.

glenn.f...@gmail.com

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Jan 18, 2023, 8:46:25 PM1/18/23
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Seems like a much needed solution for the H89.  I actually did build a Z67 interface card for the 89 and had it working with an external Z67-IDE+ but putting everything on a single board seems to make more sense.  Something to think about is whether or not you can easily make the CF devices available for removal (e.g. via a ribbon cable arrangement perhaps?)  On my Z67-IDE+ boards I remove them fairly often for a variety of reasons…

 

Glad to see some energy on H89 ideas!

 

 

 

From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of Joe Travis N6YPC
Sent: Wednesday, January 18, 2023 1:09 PM
To: SEBHC <se...@googlegroups.com>
Subject: [sebhc] H89-DCF...

 

I was so inspired by Rick Davis' design and work on the H8 Dual CF board that I decided to duplicate it for the H89.  It uses just 4 ICs, 4 diodes, 4 resistors, 2 40p IDC connectors.

 

I already know the haters are gonna poo-poo the use of 8255s but I feel there is beauty in simplicity.  Besides, I'm unaware of anyone pushing their H89s beyond 4 MHz.

 

Now I'm hoping the design will be picked up and boards created for the H89.

 

Joe

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image001.jpg
image002.jpg

Joseph Travis

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Jan 19, 2023, 11:25:35 AM1/19/23
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Norberto,

I essentially used the same design as Rick (the first version of the board you did for the H8) with some changes for use with the H89.  The only two types of ICs I used
are the 8255 and 74LS14 (two each, one for each channel).  By not implementing additional / external LEDs, a spare inverter is available in each 74LS14.  I used one
inverter for the RESET L line and the other is used for A2 along with the I/O L decode line (on pin 12).

Stupid me, I laid out and started wiring the board without a schematic.  I had many wires down and soldered before I realized I needed a couple OR gates for the I/O
address decoding.  Not wanting to tear up the wiring I put down in order to add another IC, I instead used 4 diodes and 2 resistors to form the equivalent OR gates I
needed.  The resistors are used as pull downs on the cathodes of the diodes and works fine.

If you want to use your new high speed design or this one, it doesn't matter much to me.  I just feel the H89 is long over due for something such as this.

Thanks again,
Joe
 

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Douglas Miller

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Jan 19, 2023, 11:45:42 AM1/19/23
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Norberto and I have been mulling over an idea for the H89, to basically stretch a "mezzanine" board between the I/O and memory expansion slots. Still in the planning stages, but that would allow for closing the gap between current H8 capabilities and the H89.

See attached image.

H89-addon-mezz2.png

Joseph Travis

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Jan 19, 2023, 11:57:25 AM1/19/23
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Passed the "smoke test" !


To view this discussion on the web visit https://groups.google.com/d/msgid/sebhc/cd92a1ed-d36a-024a-3c94-7b865eb6789e%40gmail.com.
20230119_042019.jpg

rw...@robhome.com

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Jan 19, 2023, 12:50:52 PM1/19/23
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Looks great!

Rob Waggoner
________________________________
From: se...@googlegroups.com <se...@googlegroups.com> on behalf of Joseph Travis <jtravi...@gmail.com>
Sent: Thursday, January 19, 2023 10:57:09 AM
To: sebhc Google Group <se...@googlegroups.com>
Subject: Re: [sebhc] H89-DCF...

Passed the "smoke test" !


On Thu, Jan 19, 2023 at 11:45 AM Douglas Miller <durga...@gmail.com<mailto:durga...@gmail.com>> wrote:

Norberto and I have been mulling over an idea for the H89, to basically stretch a "mezzanine" board between the I/O and memory expansion slots. Still in the planning stages, but that would allow for closing the gap between current H8 capabilities and the H89.

See attached image.


On 1/19/23 10:25, Joseph Travis wrote:
Norberto,

I essentially used the same design as Rick (the first version of the board you did for the H8) with some changes for use with the H89. The only two types of ICs I used
are the 8255 and 74LS14 (two each, one for each channel). By not implementing additional / external LEDs, a spare inverter is available in each 74LS14. I used one
inverter for the RESET L line and the other is used for A2 along with the I/O L decode line (on pin 12).

Stupid me, I laid out and started wiring the board without a schematic. I had many wires down and soldered before I realized I needed a couple OR gates for the I/O
address decoding. Not wanting to tear up the wiring I put down in order to add another IC, I instead used 4 diodes and 2 resistors to form the equivalent OR gates I
needed. The resistors are used as pull downs on the cathodes of the diodes and works fine.

If you want to use your new high speed design or this one, it doesn't matter much to me. I just feel the H89 is long over due for something such as this.

Thanks again,
Joe


On Wed, Jan 18, 2023 at 6:56 PM norberto.collado koyado.com<http://koyado.com> <norberto...@koyado.com<mailto:norberto...@koyado.com>> wrote:
No problem. I will help you with the board layout. Do you have some handmade schematics that you could share or just use same schematic for Ricks board adapted to the H89?

Get Outlook for iOS<https://aka.ms/o0ukef>
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From: se...@googlegroups.com<mailto:se...@googlegroups.com> <se...@googlegroups.com<mailto:se...@googlegroups.com>> on behalf of Joseph Travis <jtravi...@gmail.com<mailto:jtravi...@gmail.com>>
Sent: Wednesday, January 18, 2023 3:01:22 PM
To: se...@googlegroups.com<mailto:se...@googlegroups.com> <se...@googlegroups.com<mailto:se...@googlegroups.com>>
Subject: Re: [sebhc] H89-DCF...

Thank you Norberto! It would be nice to show the H89 some love!

On Wed, Jan 18, 2023, 3:17 PM norberto.collado koyado.com<http://koyado.com> <norberto...@koyado.com<mailto:norberto...@koyado.com>> wrote:
When using the 82C55 you can drive SATA drives with the SATA to IDE adapter. This works on the Z67-IDE+. It is easier to use the CF or SD card. You can use an SD to IDE adapter. Only one SD card is supported by the Z67-IDE+ controller.

Get Outlook for iOS<https://aka.ms/o0ukef>
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From: se...@googlegroups.com<mailto:se...@googlegroups.com> <se...@googlegroups.com<mailto:se...@googlegroups.com>> on behalf of Joseph Travis <jtravi...@gmail.com<mailto:jtravi...@gmail.com>>
Sent: Wednesday, January 18, 2023 12:06:21 PM
To: se...@googlegroups.com<mailto:se...@googlegroups.com> <se...@googlegroups.com<mailto:se...@googlegroups.com>>
Subject: Re: [sebhc] H89-DCF...

I'm not sure what purpose that would serve. Due to the limitations of HDOS and CP/M, you reach a point of diminishing returns once you go beyond 16MB.


On Wed, Jan 18, 2023 at 2:53 PM rw...@robhome.com<mailto:rw...@robhome.com> <rw...@robhome.com<mailto:rw...@robhome.com>> wrote:
Are there drive size limitations on the GIDE drives? I ask because I'm wondering if we could use an IDE to SATA converter to use larger SATA drives.

Rob Waggoner
________________________________
From: se...@googlegroups.com<mailto:se...@googlegroups.com> <se...@googlegroups.com<mailto:se...@googlegroups.com>> on behalf of Terry Gulczynski <terr...@cfl.rr.com<mailto:terr...@cfl.rr.com>>
Sent: Wednesday, January 18, 2023 12:31:35 PM
To: sebhc Google Group <se...@googlegroups.com<mailto:se...@googlegroups.com>>
Subject: Re: [sebhc] H89-DCF...

Joe,

Re: your comment about H89s over 4MHz...

I have 2 H89's running @ 12MHz and one at 8MHz. I sold a fourth one a
couple years ago that also ran at 12MHz. All four machines include a
double IDE port design based on the original GIDE by Tilmann Reh, along
with 1MB of Static RAM.

ANY design is welcome to me - 8255 works just fine.


Terry

On 1/18/2023 1:08 PM, Joe Travis N6YPC wrote:
> I was so inspired by Rick Davis' design and work on the H8 Dual CF board
> that I decided to duplicate it for the H89. It uses just 4 ICs, 4
> diodes, 4 resistors, 2 40p IDC connectors.
>
> I already know the haters are gonna poo-poo the use of 8255s but I feel
> there is beauty in simplicity. Besides, I'm unaware of anyone pushing
> their H89s beyond 4 MHz.
>
> Now I'm hoping the design will be picked up and boards created for the H89.
>
> Joe
> 20230118_115555.jpg20230118_112209.jpg
>
> --
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> To view this discussion on the web visit
> https://groups.google.com/d/msgid/sebhc/56f90223-9144-4d20-a079-5cb99fca6e58n%40googlegroups.com <https://groups.google.com/d/msgid/sebhc/56f90223-9144-4d20-a079-5cb99fca6e58n%40googlegroups.com?utm_medium=email&utm_source=footer>.

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norberto.collado koyado.com

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Jan 19, 2023, 4:21:59 PM1/19/23
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Thank Douglas for the H89 mezzanine reminder. We did work in this, and I need to find the files in the computer. Do we need to review what devices we need now as a lot has changed?
From: se...@googlegroups.com <se...@googlegroups.com> on behalf of rw...@robhome.com <rw...@robhome.com>
Sent: Thursday, January 19, 2023 9:50:46 AM

To: sebhc Google Group <se...@googlegroups.com>
Subject: Re: [sebhc] H89-DCF...
Looks great!

Rob Waggoner
From: se...@googlegroups.com <se...@googlegroups.com> on behalf of Joseph Travis <jtravi...@gmail.com>
Sent: Thursday, January 19, 2023 10:57:09 AM
To: sebhc Google Group <se...@googlegroups.com>
Subject: Re: [sebhc] H89-DCF...
 
Passed the "smoke test" !


On Thu, Jan 19, 2023 at 11:45 AM Douglas Miller <durga...@gmail.com> wrote:

Norberto and I have been mulling over an idea for the H89, to basically stretch a "mezzanine" board between the I/O and memory expansion slots. Still in the planning stages, but that would allow for closing the gap between current H8 capabilities and the H89.

See attached image.


On 1/19/23 10:25, Joseph Travis wrote:
Norberto,

I essentially used the same design as Rick (the first version of the board you did for the H8) with some changes for use with the H89.  The only two types of ICs I used
are the 8255 and 74LS14 (two each, one for each channel).  By not implementing additional / external LEDs, a spare inverter is available in each 74LS14.  I used one
inverter for the RESET L line and the other is used for A2 along with the I/O L decode line (on pin 12).

Stupid me, I laid out and started wiring the board without a schematic.  I had many wires down and soldered before I realized I needed a couple OR gates for the I/O
address decoding.  Not wanting to tear up the wiring I put down in order to add another IC, I instead used 4 diodes and 2 resistors to form the equivalent OR gates I
needed.  The resistors are used as pull downs on the cathodes of the diodes and works fine.

If you want to use your new high speed design or this one, it doesn't matter much to me.  I just feel the H89 is long over due for something such as this.

Thanks again,
Joe
 

On Wed, Jan 18, 2023 at 6:56 PM norberto.collado koyado.com <norberto...@koyado.com> wrote:
No problem. I will help you with the board layout. Do you have some handmade schematics that you could share or just use same schematic for Ricks board adapted to the H89?
Sent: Wednesday, January 18, 2023 3:01:22 PM
To: se...@googlegroups.com <se...@googlegroups.com>
Subject: Re: [sebhc] H89-DCF...
 
Thank you Norberto! It would be nice to show the H89 some love!

On Wed, Jan 18, 2023, 3:17 PM norberto.collado koyado.com <norberto...@koyado.com> wrote:
When using the 82C55 you can drive SATA drives with the SATA to IDE adapter. This works on the Z67-IDE+. It is easier to use the CF or SD card. You can use an SD to IDE adapter. Only one SD card is supported by the Z67-IDE+ controller.
Sent: Wednesday, January 18, 2023 12:06:21 PM
To: se...@googlegroups.com <se...@googlegroups.com>
Subject: Re: [sebhc] H89-DCF...
 
I'm not sure what purpose that would serve.  Due to the limitations of HDOS and CP/M, you reach a point of diminishing returns once you go beyond 16MB.


On Wed, Jan 18, 2023 at 2:53 PM rw...@robhome.com <rw...@robhome.com> wrote:
Are there drive size limitations on the GIDE drives?  I ask because I'm wondering if we could use an IDE to SATA converter to use larger SATA drives.

Rob Waggoner
________________________________
From: se...@googlegroups.com <se...@googlegroups.com> on behalf of Terry Gulczynski <terr...@cfl.rr.com>

Sent: Wednesday, January 18, 2023 12:31:35 PM
To: sebhc Google Group <se...@googlegroups.com>
Subject: Re: [sebhc] H89-DCF...

Joe,

Re: your comment about H89s over 4MHz...

I have 2 H89's running @ 12MHz and one at 8MHz.  I sold a fourth one a
couple years ago that also ran at 12MHz.  All four machines include a
double IDE port design based on the original GIDE by Tilmann Reh, along
with 1MB of Static RAM.

ANY design is welcome to me - 8255 works just fine.


Terry

On 1/18/2023 1:08 PM, Joe Travis N6YPC wrote:
> I was so inspired by Rick Davis' design and work on the H8 Dual CF board
> that I decided to duplicate it for the H89.  It uses just 4 ICs, 4
> diodes, 4 resistors, 2 40p IDC connectors.
>
> I already know the haters are gonna poo-poo the use of 8255s but I feel
> there is beauty in simplicity.  Besides, I'm unaware of anyone pushing
> their H89s beyond 4 MHz.
>
> Now I'm hoping the design will be picked up and boards created for the H89.
>
> Joe
> 20230118_115555.jpg20230118_112209.jpg
>
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norberto.collado koyado.com

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Jan 19, 2023, 4:23:27 PM1/19/23
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Joe, how can I get a copy of the image you have on such CF cards?
From: se...@googlegroups.com <se...@googlegroups.com> on behalf of norberto.collado koyado.com <norberto...@koyado.com>
Sent: Thursday, January 19, 2023 1:21:53 PM

Joseph Travis

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Jan 19, 2023, 5:27:01 PM1/19/23
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I'm using my H8 with the original H8 DCF board to PREP and PARTition the CFs.  I believe Rick is still in the process of updating the software to be able to accept a port address (as opposed to a channel number).

There is no immediate plan to modify / update H89 ROM(s) to boot from the CF (as work is still needed on the H8) although it has been discussed. This will likely take a similar route as the H8 DCF, using a floppy to boot first.

Do we have known good source code for ROMs MTR-89 (444-62) and MTR-90 (444-142)?

Joe


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Douglas Miller

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Jan 19, 2023, 5:41:55 PM1/19/23
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(split thread.... sorry)

Yes, I think we should review the hardware we try to squeeze on the H89 mezz. Instead of GIDE, use direct-CF maybe. Might also drop the WizNET/SPI. Probably keep the H89-512K-MMU, RTC, and see about adding the 28C256 EEPROM? I'm thinking of "new" devices that we have difficulty assigning I/O port address on the H89 due to it's restricted I/O slots. Lots to discuss...

Richard Davis Jr.

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Jan 19, 2023, 8:04:43 PM1/19/23
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Norberto,

I have wanted to do that but I haven't really looked for a linux DD equivalent for Windows to create an image.

Rick


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norberto.collado koyado.com

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Jan 19, 2023, 9:12:10 PM1/19/23
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Yes, for the MTR-90 and thanks to Terry G. I will send tonight once I get home.
From: se...@googlegroups.com <se...@googlegroups.com> on behalf of Richard Davis Jr. <rickdav...@gmail.com>
Sent: Thursday, January 19, 2023 5:04:28 PM

norberto.collado koyado.com

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Jan 19, 2023, 9:13:29 PM1/19/23
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Rick, I will send info tonight to do the imaging,
Sent: Thursday, January 19, 2023 6:12:02 PM

norberto.collado koyado.com

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Jan 19, 2023, 11:41:34 PM1/19/23
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MTR-90 Source code by Terry Gulczynski (terr...@cfl.rr.com)

MTR90.zip   - (Pseudo ops in the file are specific to the Zilog Development System -(ZDS) v3.68.

Zilog Developer Studio I version 3.68: ZDS368.exe.zip

norberto.collado koyado.com

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Jan 19, 2023, 11:49:44 PM1/19/23
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Z67-IDE Imaging Utility

Z67-IDE Windows Imaging Utility.zip

 

Also try installing Cygwin64 terminal under Windows.

 

glenn.f...@gmail.com

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Jan 20, 2023, 9:54:03 AM1/20/23
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The HDD Raw Copy tool (“Windows Imaging Utility” link from Norberto). Has worked very nicely for me. I use it to backup and restore CF devices all the time. It can also create and read compressed backups.  It is free.  I believe it uses a proprietary format so if you need to exchange with someone who isn’t a Windows user then something like dd is a better option, but for personal use I’ve found the HDD Raw Copy tool to be a good choice…

 

  • Glenn
image001.png

Douglas Miller

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Jan 20, 2023, 10:50:39 AM1/20/23
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I was eventually able to find a Linux utility to read Norberto's images. I have been using https://github.com/Shizmob/unimgc.git

rand...@hotmail.com

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Jan 20, 2023, 1:02:52 PM1/20/23
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I am under the belief these tools are all just straight linear sectors just like dd. The most common form of image backups removing all hardware considerations. 

There are other formats like IMD/TD0 when you need to include formatting details.

Some imaging software can do raw as well as formatted imaging. 

Basically "raw" means no coding just raw data.


Randy

Douglas Miller

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Jan 20, 2023, 1:15:29 PM1/20/23
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Not true for HDD Raw Copy tool, you cannot easily transform that into a raw image of sectors without some program that decodes the image format.

Joseph Travis

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Jan 20, 2023, 3:19:33 PM1/20/23
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During my board checkout process, I discovered that due to the H89 I/O programming scheme we may be limited to 1 CF channel.  Each CF channel requires 4 port I/O addresses.  Floppy disk I/O mapping uses 170Q-173Q and 174Q-177Q (used for the H17).  One is better than none but, if a board is to be made, I suggest having jumpers to be able to select different I/O ports.  Some may choose to sacrifice a serial I/O port in favor of having 2 CF drives.  Thoughts?

Joe


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glenn.f...@gmail.com

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Jan 20, 2023, 4:17:53 PM1/20/23
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The Z67 had jumpers to allow it to be addressed at 17x or 27x but I don’t believe any of their standard software configurations supported the 27x settings.  With an H17 you’d have the H17 at 174Q and either H37 or Z67 at 170Q.  If you didn’t have an H17 then the H37 would be at 170 and Z67 at 174. 

 

With Norberto’s re-engineered 37/67 interface board you no longer have to stick to the Heath conventions. We have configurations that support the 27x assignment, so now you can have all three drives active: H17 at 174, H37 at 170 and Z67 at 270 or 274.

 

So are the 27x ranges an option for this situation?

Douglas Miller

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Jan 20, 2023, 4:20:28 PM1/20/23
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Magnolia Microsystems did something to expand the H89 I/O ports available, but I don't think that has been widely adopted here. They changed the I/O decoder PROM so that the three serial port signals were now a binary pattern, expanding 3 devices (port ranges) to 7. This did mean that the standard Heath serial port card could not be used (without modification), but MMS also made their own serial card as well as added the serial ports to several other cards (like the H67-equivalent). The 8250 made this easy since it has 3 chip-select lines and they are the right polarity to just work without extra gates.

But, this is part of the reason for the H89-Mezannine card - the devices on the mezzanine can use any port ranges we want.

Douglas Miller

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Jan 20, 2023, 4:22:18 PM1/20/23
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Note, the H89 does not have the option of using ports 27x. The I/O decoder does not generate any signal for that port range.

glenn.f...@gmail.com

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Jan 20, 2023, 4:23:11 PM1/20/23
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My H89 ignorance is showing…

Joseph Travis

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Jan 20, 2023, 4:23:17 PM1/20/23
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That's easy enough to do on a H8 however, the H89 uses a PROM for I/O address decoding.  It appears Doug has a solution that I also thought of but that requires a new I/O decoder PROM.

Douglas Miller

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Jan 20, 2023, 4:44:43 PM1/20/23
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"we" do have this MMS I/O decoder around, I think it is named "444-61C". Or something like that.

Douglas Miller

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Jan 20, 2023, 4:50:21 PM1/20/23
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The MMS documentation for their 444-84B monitor ROM has a pretty good description of that they did, In APPENDIX B of this document http://sebhc.durgadas.com/mms89/docs/mms-monitor-84b.pdf

Joseph Travis

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Jan 20, 2023, 5:06:16 PM1/20/23
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Another thought I had is to use bit D3 of port 362Q to select which CF to use.  However, I'm aware that some H89 speed mods may use that for switching CPU speed.

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Joseph Travis

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Jan 20, 2023, 5:12:44 PM1/20/23
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Looking at the H89 CPU board schematics, I/O port 362Q bits D6 and D7 are already routed to the bus.  We could probably use one of those signals to select which CF to use... I think this might be the answer.

Douglas Miller

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Jan 20, 2023, 5:18:24 PM1/20/23
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So, bit 6 of 362Q is the H17 side select.

We're also using bit 7 now to enable flashing the EEPROM on new systems. That may be on the H8 (for now...), but keeping the H8 and H89 as software-compatible as possible would be a good thing.

Joseph Travis

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Jan 20, 2023, 5:24:27 PM1/20/23
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Yep.  So it looks like 362Q bit 6 is the way to go.

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Douglas Miller

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Jan 20, 2023, 5:35:43 PM1/20/23
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The reason you rarely see one single bit being used to select two storage devices is that it leaves one of those devices vulnerable at all times (there is no "none selected" state) - higher risk of corrupting the media if anything does unintentional I/O to that range (or during power-on/off/RESET). Note how floppies and HDDs all have discrete select lines.

If you make this incompatible with the H17 by using it's side-select line (bit 6), you will be restricting the audience for this board. If you are only talking about a one-off, you are certainly free to implement it as you wish. I'm just making sure you have all the information.

Joseph Travis

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Jan 20, 2023, 5:50:51 PM1/20/23
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I don't believe it will be a problem.  Bit 6 (I/O 0H) and 7 (I/O 1H) are routed to all 3 slots and (I believe) available as needed by any board for whatever purpose.  I suspect the H17 driver(s) use it as needed.  I'll find out one way or another!


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Douglas Miller

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Jan 20, 2023, 5:54:25 PM1/20/23
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I'm not sure I'm getting my point across. The H17 has already claimed bit 6 for side-select. This means that both boards cannot be used in an H89 at the same time.

You might consider using a port multiplexer scheme, like what the H37 does. It's able to access all 4 WD1797 ports plus two H37 control/status ports using only a 4-port range.

Joseph Travis

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Jan 20, 2023, 7:35:57 PM1/20/23
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I understand what you're saying, I just don't believe it is exclusive. Nevertheless, after more thought I believe it would be easier to deal with (software wise) not to use a separate port to select which CF to use. 

The software that exists now uses 1 base port address and expects 8 contiguous ports for 2 CF channels. I think we have options here. (1) You can use 1 CF if using port 170Q or (2) you can use 2 CFs if you are willing to sacrifice one of your serial ports.

norberto.collado koyado.com

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Jan 20, 2023, 10:26:46 PM1/20/23
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Please use ports 333Q, 334Q, 335Q, 336Q and 337Q. Ports 330Q, 331Q, and 332Q are used by the VDIP1 and FT245 Controller on the H89 computer.
Sent: Friday, January 20, 2023 4:35:41 PM

norberto.collado koyado.com

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Jan 21, 2023, 12:46:53 AM1/21/23
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On the H89 going forward the best solution is to use the mezzanine solution from Douglas with CPU speed control. Easy to add features.

 

Norberto

Joseph Travis

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Jan 21, 2023, 11:01:13 AM1/21/23
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I can do that. Fortunately it is an easy one wire change. I'll be using ports 170Q-173Q for CF1 and ports 334Q-337Q for CF2.

I think it would be wise to use configuration jumpers for this board when it gets spun. Not everyone will have the same configuration for their H89 as you or me.  It offers flexibility and the software will allow configuring by port address.

The mezzanine board discussion should be spun off in another thread but as long as I have your attention, wouldn't it be better and easier to just create a new CPU board with the desired features rather than cramming on top of the existing board, adding additional load to the power supply, not to mention the additional points of failure?  Just my two cents...

Joe

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Douglas Miller

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Jan 21, 2023, 11:14:01 AM1/21/23
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That is another option, however that large of a board is expensive, from
what I hear, and more complicated. The power concern is mitigated by
removal of many legacy, power-hungry, chips - mainly the DRAM. Any
add-on creates additional points of failure, you'd have to factor in
many things - like removal/replacement of the entire CPU board. There
may also be concerns about authenticity and reverting back to original
for whatever reason. A discussion worth having, though. Look forward to
hearing other thoughts.


On 1/21/23 10:00, Joseph Travis wrote:
> ...

Steven Hirsch

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Jan 21, 2023, 12:14:01 PM1/21/23
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On 1/20/23 13:02, rand...@hotmail.com wrote:
> I am under the belief these tools are all just straight linear sectors just
> like dd. The most common form of image backups removing all hardware
> considerations.

That is not the case for many (most?) of the Windows imaging tools. I would
strongly advise against the use of anything that produces or uses an
undocumented format. dd + gzip can be created and unpacked on any Linux,
Windows or Mac system.

norberto.collado koyado.com

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Jan 21, 2023, 4:44:38 PM1/21/23
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Perhaps a smaller board and define what we can fit in there.

 

 

-----Original Message-----
From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of Douglas Miller
Sent: Saturday, January 21, 2023 8:14 AM
To: se...@googlegroups.com

Subject: Re: [sebhc] H89-Mezannine

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Mark Garlanger

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Jan 21, 2023, 5:28:05 PM1/21/23
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Or instead of deleting those 3 on the left, it would be cool if you can make it so that they are useful and support any card that normally only supported being on the right side. 

I'm totally out of the loop on pricing, do we have an approximate price for a board this size? Didn't someone find a new board provider that was significantly cheaper? 

If a full board was made, maybe it could be used to upgrade an H19 to a full H89. 

Mark


Joseph Travis

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Jan 21, 2023, 10:45:57 PM1/21/23
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Mark ,
There are two problems with that idea:
(1) The left side is for memory and doesn't have I/O decoding
(2) The flyback transformer would be in the way of a full length I/O board

Doug,
Would you mind telling us that are potentially interested, what improvements / capabilities it would offer?

Thanks,
Joe


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Douglas Miller

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Jan 21, 2023, 11:03:12 PM1/21/23
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My original idea was to allow the H89 to be on-par with the H8 as far as software it could run (hardware capabilities). For example, AFAIK right now the only CP/M 3 for the H89 requires the (rare) MMS 77318 128K memory add-on. I've been providing a lot of software for the H8, and thought it might be appreciated if that could also run on the H89. The H8-512K-MMU and H8-SPI (WizNET) were two boards, and the direct-attach CF is another to add. The standard H89 just does not have the ability to handle all those add-on boards and still have the standard I/O.

I was looking for a way to expand the H89 without replacing the entire CPU board. However, if there were enough demand for a new CPU board, and it could be done economically (determines the demand I suspect), and H89 owners were willing to make that change, then it might be worth pursuing. I fear that that big of a project may not get done for years, though - at least if we dump it on Norberto to do. It's taken at over two years just to see the H8-Z180 board.

BTW, if we're doing a new CPU board then there is no reason that the slots on the left have to be memory (in fact, there's probably no reason for them to be if the main board has 512K SRAM). We can make the new board with more I/O slots (on the left), but we have to figure out how we assign ports to them (i.e. which ports to assign to which slots).

Joseph Travis

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Jan 22, 2023, 9:51:24 AM1/22/23
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Doug,

Thank you for your explanation.  It seems to me that KRES Engineering(?) and / or someone else had a mezzanine board offered back in the '80s.  I know that CDR Systems also had a 128K-512K memory board the same size as the Heathkit 16K memory expansion board.

To some degree, I like the idea however I feel it only addresses a subset of desired improvements for the H89.   If the only interest is to expand I/O capability, the mezzanine board is the way to go.  If the desire is to be able to run CP/M 3, you'll want more memory and faster CPU speed too.  

Now that Norberto has created a Z180 CPU board for the H8, I'd like to see that design leveraged for a H89 CPU board.  I have two H89s and would definitely build at least one.  If buying two boards helps bring down the cost or make the project viable, I'd do that as well.

BR,
Joe




 

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Douglas Miller

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Jan 22, 2023, 10:24:43 AM1/22/23
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I obviously have not fully explained the idea, if you believe the mezzanine would not allow CP/M 3. Faster CPU would be nice, but I did development work on a stock H89 running MMS CP/M 3 back in the day, and it was fine. There are/were speed upgrades for the H89, too.

I'll restate my concerns about redoing the whole CPU board. I'd like to know what others, who are potential consumers of the product, would think (how many people would actually buy this).

1) Dollar expense of a large-format CPU board. That determines "market".

2) Engineering expense of a full CPU board. Need brackets and support bars, etc. Plus the time for whoever is going to layout the PCB.

3) Logistics of making the modification to an H89. This is not at all like replacing a CPU board in an H8. How many are willing to make this change.

I think it would be nice to start over from scratch and build a better H89. But, if that means making the system "less of an H89" in the eyes of users then the demand is diminished. The work for me is probably minimal, but I'm just protective of Norberto's time and wonder if a project this big can be done by him along with all the other things on his list. Obviously, Norberto needs to chime-in, as well as anyone else that might volunteer to do the layout.

I viewed the mezzanine idea as more authentic (an add-on product that actually was or might have been produced in the '80s), less intrusive, and easier to revert. There were some replacement CPU boards, too, like the DG Super-89, however I don't know how many of those sold. Current sentiments might be different, too, w.r.t. maintaining the original H89 design.

I'd like to hear input from the broader group. Especially regarding those with serious interest in "buying" either the mezzanine or full CPU board. If there are those that seriously want to upgrade their H89 to be more like modern H8s, how far are they willing to go for that?

norberto.collado koyado.com

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Jan 22, 2023, 6:07:25 PM1/22/23
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The more I think about this, the more I’m incline to go with the Mezzanine card. We can start with the basics to prove out that the mezzanine will work fine. Then eventually we can evolved such board to be more powerful by adding more options.

 

Just checking an H89 board that I have on-hand, using the connector to hold the mezzanine board will provide enough clearance to stretch the board downward to the CPU section if more space is needed.

 

On the Z80, we can use the same and just replaced it with the Z80 20Mhz, add the I/O wait generator to push the I/O boards beyond 4MHz. The on-bord 8250 might need to be replaced with the 16C550 version.

 

As a team, we need to agree on what we need to add to the mezzanine board. Based on discussions:

 

  1. The mezzanine will consume one I/O slot:
    1. P506/P512 – H17 or H67
    2. P505/P511 – H37 or H67 if H17 is being used on P506/P512.
    3. P504/P510 – For mezzanine card – so we just need to add a 16C550 serial port for the modem.
  2. 16C550 serial port for modem
  3. 512KB to support CP/M3
  4. VDIP1
  5. Bring “BIORQ L” to the mezzanine board to use A0-A7 available on P503/P509 to expand I/O range. Use GAL to get additional I/O ports.
  6. Direct attached CF card (one or two??)
  7. SPi bus
  8. I/O wait generator to push H89 to 16MHz.
  9. What else?

 

 

Thanks,

Norberto

Douglas Miller

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Jan 22, 2023, 6:19:29 PM1/22/23
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I was thinking the 32K EEPROM. Also the RTC.

I'm not sure if we want to add the SPI (WizNET) or not. It also provides SDCards, but not sure how much demand there is for CP/NET. We may not need both CF and SDcard, but both have advantages and disadvantages. I'm thinking just one CF, given the space it consumes. With SDCard, we could do two. A good question for the group - would you rather use CF or SDCard for expanded storage? I suspect we could re-do the SPI using GAL/CPLD and save a lot of space on the PCB.

Do we need to add the modem UART? Was that to compensate for loss of an I/O slot? Could that be a DUART socket, for the Dual UART + VDIP1 daughter board you already have?

norberto.collado koyado.com

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Jan 22, 2023, 7:58:18 PM1/22/23
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Updates for review:

 

    1. The mezzanine will consume one I/O slot:
      1. P506/P512 – H17 or H67 or Serial 0 and Serial 1 8250 controllers.
      1. P505/P511 – H37 or H67 if H17 is being used on P506/P512.
      2. P504/P510 – For mezzanine card
      1. 512KB to support CP/M3
      2. Bring “BIORQ L” on pin 15 – U550 to the mezzanine board to use A0-A7 available on P503/P509 to expand I/O range. Use GAL to get additional I/O ports. Solder a cable to this pin.
      3. One Direct attached CF card
      4. One/two SD SPi bus
      1. I/O wait generator to push H89 to 16MHz.
        1. S0 is on pin 16 P509.
        2. S1 is on pin 6  U552 – solder a wire to this location.
      1. DUART module -with additional serial ports + VDIP1.
      2. RTC
      3. A0-A12 on P509 – need to bring A13, A14, A15 to mezzanine card. They are at U517 pin 1, 2, 3.
        1. Note: Remove U517 ROM and bring signals to the Mezzanine board. Insert ROM onto mezzanine board along with a 20 pin cable.
      4. 32KB ROM with /ROMDIS signal (on U517 pin 19) & MEM1 (on pin 17 P509) & MREQ (on U517 – pin 15)

      Joseph Travis

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      Jan 25, 2023, 10:25:16 PM1/25/23
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      Many thanks to Rick Davis for his work on the Dual CF software!  The H89-DCF is working!  Shown in the photos are files being transferred using MegaPIP, from the bottom CF (borrowed from my H8-DCF) to the upper CF.  The last photo shows drives CA0: - CA7: mounted.

      --
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      20230125_195617.jpg
      20230125_195630.jpg
      20230125_214900.jpg

      norberto.collado koyado.com

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      Jan 25, 2023, 11:55:39 PM1/25/23
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      Wow! I’m impressed and nicely done!

       

      Norberto

       

      From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of Joseph Travis
      Sent: Wednesday, January 25, 2023 7:25 PM
      To: se...@googlegroups.com

      Subject: Re: [sebhc] H89-DCF...

      Glenn Roberts

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      Jan 26, 2023, 4:40:47 AM1/26/23
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      Nicely done Joe and Rick! Congrat’s!

      Sent from my iPad

      On Jan 25, 2023, at 11:55 PM, norberto.collado koyado.com <norberto...@koyado.com> wrote:

      

      norberto.collado koyado.com

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      Jan 26, 2023, 4:30:08 PM1/26/23
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      Next steps to get the Direct Attach CF booting HDOS and CPM. Then afterwards I can get the H89 version as well.
      From: se...@googlegroups.com <se...@googlegroups.com> on behalf of Glenn Roberts <glenn.f...@gmail.com>
      Sent: Thursday, January 26, 2023 1:40:33 AM
      To: se...@googlegroups.com <se...@googlegroups.com>
      Subject: Re: [sebhc] H89-DCF...
       

      norberto.collado koyado.com

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      Jan 28, 2023, 7:00:43 PM1/28/23
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      Douglas,

       

      Attached is a picture of space that we can use pending final review..

       

      The RAM, ROM, and RTC can go at the bottom of the mezzanine board.

       

      The CF, SD, DUART can go at middle top of the mezzanine  board.

       

      Any thoughts,

       

      Norberto

       


      Date: Sunday, January 22, 2023 at 4:58 PM
      To: se...@googlegroups.com <se...@googlegroups.com>

      Subject: RE: [sebhc] H89-Mezannine

      h89_mezzanine_size.jpg

      Douglas Miller

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      Jan 28, 2023, 7:08:33 PM1/28/23
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      Sounds like a plan.

      For the SD (SPI), do you plan on adding capability to install the WizNET module? Just wondering, as that might want to be near the top, too (but less important). If you're adding the SPI, there's not much "cost" to adding a place for the WizNET headers - maybe. That would also mean the SPI EEPROM too (but that's just an 8-pin DIP and needn't be super-accessible).

      My other thought was on how far down the mezzanine extends. How close does the PCB get to the CRT yoke in that case? Do we have any concerns there, with electrical interference or heat? Just wondering, as I don't know that much about those circuits except to not touch them.

      Douglas Miller

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      Jan 28, 2023, 7:09:38 PM1/28/23
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      Oh, and one more: do we need to leave a cut-out for the ROM jumpers - if all the ROM/RAM moves to the mezzanine?

      norberto.collado koyado.com

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      Jan 28, 2023, 7:45:17 PM1/28/23
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      Do we need to leave a cut-out for the ROM jumpers – Do you mean on the H89 board? yes.

       

      SPI EEPROM will be there. Yes, planning on WIzNET, but it takes space as the VDIP1, CF card does. Let’s see how it fits.

       

      My other thought was on how far down the mezzanine extends. How close does the PCB get to the CRT yoke in that case? Do we have any concerns there, with electrical interference or heat?

       

      I can use the H8 half size+ board to get some measurements as shown in the attached picture.  Not concerned about heat as the H89 has a fan to keep air circulating. More concerned about EMI. All the small parts can go at the bottom.

       

      Norberto

      Proto_size_test.jpg

      Douglas Miller

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      Jan 28, 2023, 8:49:32 PM1/28/23
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      Re: cut-out, I guess the jumper pins stick up too far? Because otherwise they are not needed when the RAM/ROM reside on the mezzanine.

      I guess the upper-left corner need not be cut-out, as there's no need for the memory slots (and bracket) anymore?

      Douglas Miller

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      Jan 28, 2023, 8:56:26 PM1/28/23
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      Also, regarding heat: I was talking about localized heat from the neck of the CRT. Although, I don't remember the H89's having fans.

      I'm assuming that (at least) the DRAM and EPROMs are depopulated when installing the Mezzanine - but are we considering that "too invasive"? It would certainly cut down on heat and power consumption.

      Mark Garlanger

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      Jan 28, 2023, 9:25:58 PM1/28/23
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      The H89 had a fan over the power supply. I think it was pointed out, but there were huge debates on which directions would be better, and whether or not to cut out the above the fan to allow better flow.

      Mark

      To view this discussion on the web visit https://groups.google.com/d/msgid/sebhc/71219df9-8efc-3f59-9b7e-4bbaa53e6865%40gmail.com.

      norberto.collado koyado.com

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      Jan 29, 2023, 12:55:12 AM1/29/23
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      Based on the attached picture, no concerns with heat and EMI.

       

      At the bottom of an older H89 that I have there is the flyback screw touching the pcb. I have to cut the board above the plate as any IC below cannot use an IC socket.

       

      So, it makes sense to extend the mezzanine to the left side as those memory connectors are no longer in use to get more space for layout.

       

      I'm assuming that (at least) the DRAM and EPROMs are depopulated when installing the Mezzanine - but are we considering that "too invasive"?

       

      I will need to review the schematics on how to disabled the ROM’s and RAM’s without the need to take them out as it is too much work to do.

       

      Steps to install mezzanine:

      1. Power Down H89
      2. Remove H89 Computer board
      3. Disable on board ROM’s/RAMS – tristate.
      4. Remove the left bracket
      5. Remove 16KB board
      6. Install mezzanine board
      7. Install cables
      8. Insert H89 Computer board
      9. Power-up H89
      10. Done!

       

      Flyback screw interference: No need to go that low.

       

       

      Do not go below this line as cannot use IC sockets.

       

       

      Hope this helps,

       

      Norberto

      Mezzanine_measurements.jpg

      norberto.collado koyado.com

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      Jan 29, 2023, 1:56:43 AM1/29/23
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      As I mentioned no concerns about EMI. The reason is that the 16KB RAM board that the H89 uses, it is sitting on top of the flyback and closer to the tube and it works fine.

       

      The mezzanine is a cleaner/better solution. 😊

       

      norberto.collado koyado.com

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      Jan 29, 2023, 3:27:47 AM1/29/23
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      See attached file and this is approx. what we can get for the Mezzanine board size.

      Mez_card_real-state.jpg

      Steven Hirsch

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      Jan 29, 2023, 9:38:48 AM1/29/23
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      On 1/29/23 01:56, norberto.collado koyado.com wrote:
      > As I mentioned no concerns about EMI. The reason is that the 16KB RAM board that the H89 uses, it is sitting on top of the flyback and closer to the tube and it works fine.
      >
      > The mezzanine is a cleaner/better solution. 😊
      >
      > [cid:image0...@01D9336B.86D0D310]
      >

      I'm seeing an increasing number of posts with this odd 'cid:...' URL link.
      Thunderbird cannot resolve this to an image. Is it just me?

      Douglas Miller

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      Jan 29, 2023, 9:43:19 AM1/29/23
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      I don't see it, and I'm also using Thunderbird (Linux, Ubuntu 22.04).
      That appears to be an embedded image (in my copy of that email, I see
      the image), as opposed to an attached image file. Is Thunderbird showing
      a warning bar at the top, saying it is protecting you from remote
      content or some such thing? Maybe your Thunderbird settings are hiding
      the image by default?

      Steven Hirsch

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      Jan 29, 2023, 11:32:47 AM1/29/23
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      Figured it out. Under 'View' I needed to specify 'html' rather than plain text.

      Douglas Miller

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      Jan 29, 2023, 7:55:03 PM1/29/23
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      That looks like a lot of space, but I guess it is smaller that a full-sized H8 board. Is that about 7"x5", minus the cut-out?

      In my opinion, the CF is going to be the biggest use of board space at the top. I'm of the opinion that the WizNET + 2xSDCard is a better use of space - if it comes down to one or the other. You get network and two storage cards for about as much space as one CF socket. Others will want to weigh-in on SDCard vs. CF. You see how tight space gets.

      The other option would be to put the serial capabilities back onto an add-on card - at least the H89 has a console port regardless (the DUART would be providing only supplemental serial ports, and the VDIP).

      Or, we think about a way to add another I/O slot or expansion mechanism (a daughter board on top of the mezzanine on top of the main CPU board? Or an I/O slot who's card lays flat, parallel to the mezzanine? Or an extended/modified bracket that allows one add-on card to rise up further from the main board?).

      On 1/29/23 02:27, norberto.collado koyado.com wrote:

      See attached file and this is approx. what we can get for the Mezzanine board size.

       

      Norberto

       

      From: se...@googlegroups.com <se...@googlegroups.com> on behalf of norberto.collado koyado.com <norberto...@koyado.com>
      Date: Saturday, January 28, 2023 at 10:56 PM
      To: se...@googlegroups.com <se...@googlegroups.com>
      Subject: RE: [sebhc] H89-Mezannine

      As I mentioned no concerns about EMI. The reason is that the 16KB RAM board that the H89 uses, it is sitting on top of the flyback and closer to the tube and it works fine.

       

      The mezzanine is a cleaner/better solution. 😊

       


       

      From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of norberto.collado koyado.com


      Sent: Saturday, January 28, 2023 9:55 PM
      To: se...@googlegroups.com
      Subject: RE: [sebhc] H89-Mezannine

       

      Based on the attached picture, no concerns with heat and EMI.

       

      At the bottom of an older H89 that I have there is the flyback screw touching the pcb. I have to cut the board above the plate as any IC below cannot use an IC socket.

       

      So, it makes sense to extend the mezzanine to the left side as those memory connectors are no longer in use to get more space for layout.

       

      I'm assuming that (at least) the DRAM and EPROMs are depopulated when installing the Mezzanine - but are we considering that "too invasive"?

       

      I will need to review the schematics on how to disabled the ROM’s and RAM’s without the need to take them out as it is too much work to do.

       

      Steps to install mezzanine:

      1. Power Down H89
      2. Remove H89 Computer board
      3. Disable on board ROM’s/RAMS – tristate.
      4. Remove the left bracket
      5. Remove 16KB board
      6. Install mezzanine board
      7. Install cables
      8. Insert H89 Computer board
      9. Power-up H89
      10. Done!

       

      Flyback screw interference: No need to go that low.

       


       

      Do not go below this line as cannot use IC sockets.

       


       

      Hope this helps,

      norberto.collado koyado.com

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      Jan 30, 2023, 1:10:39 AM1/30/23
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      Is that about 7"x5", minus the cut-out? Not sure, as I cannot find my ruler. ☹ Yes, it is smaller than a full size H8 board.

       

      Or, we think about a way to add another I/O slot or expansion mechanism (a daughter board on top of the mezzanine on top of the main CPU board?

      We need to define what makes sense to have on the mezzanine card. Adding a second board on top of the mezzanine, is possible, but we need to define what goes in there.

       

      Or an I/O slot who's card lays flat, parallel to the mezzanine?  This is possible as it will be in parallel with the mezzanine board. Which H89 board goes in here?

       

      Or an extended/modified bracket that allows one add-on card to rise up further from the main board?). I cannot visualized this ask. Need a picture or sketch.

       

      Norberto.

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