PCB for Heathkit H8 Computer

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Steven Feinsmith

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Feb 1, 2021, 8:21:15 AM2/1/21
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I reviewed Les Bird, and SEBHC contained PCB files. It allows me to order PCB through PCBWAY (China). In the past, I ordered several PCB for my projects through the PCBWAY. They showed me excellent service and a beautiful PCB without any problems. I decided to use PCBWAY to make H8 boards.

I discovered the Gerber files were useless. They were not able to open through my KiCAD or Eagle. The files on my computer turned into Adobe Photoshop. Strange incident? After, I discovered the PHO extension was wrong as the O was a letter instead of a number. I change the type extension with a number, and it showed as for the Viewmate program.

Then I have to use Pentalogix PCB maker. I was shocked about the charge for the  PCB service was $275 with ten pieces (minimum) plus shipping charge. It will cost me over $1000 for the boards that I need to build the H8. Is it much cheaper to purchase a used H8 from eBay?

I wonder if you may give me the advice to find a way to get the PCBs with correct Gerber and other files combined. Also, I need to rework on front panel board to accept 1" alphanumeric display components and possibly to change transistors to handle a bit higher current demand. I have it in my tray contained 10 pieces for more than 15 years and want to use it.

I learn about Molex connectors for the board now at $10 apiece?

Thanks,
Steven

Glenn Roberts

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Feb 1, 2021, 10:55:54 AM2/1/21
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Steven: I know you’ve been trying to reestablish your H8 capability ever since the unfortunate theft of your old equipment. For what it’s worth I offer a few thoughts.

 

  • It sounds like you are considering rolling your own from “scratch” including a custom chassis?  Perhaps something like Terry Gulczynski did? https://sebhc.github.io/sebhc/memberphotos.html?  That would be a very interesting endeavor!
  • Regardless of your approach this will cost money.  I think you should budget $1000 to get a system up and running whether you do it all from scratch or by starting with an eBay find.
  • If your heart isn’t into doing the 100% from scratch approach, consider starting with something from eBay and repairing/improving..  there’s a nice system out there now that I bet will go for close to $1,000 (maybe more!?)  by the time bidding is over: https://www.ebay.com/itm/Vintage-Heathkit-H8-computer-with-floppy-drive-cabinet-and-3-x-5-Floppy-Drives/303862878063
  • While it would be cool to build Les’ boards from 2009 there are more modern boards you could consider.  If it were me I’d get as plain an H8 as possible from eBay – that gives you the chassis, power supply, backplane and front panel, then enhance it with some of Norberto’s latest designs.  With just two of his boards (the Z80 CPU/serial/USB/RAM/RTC combo and the H37/67/17 I/O board) you can have a very complete and powerful system!  If your eBay purchase included boards you don’t need you could offset your costs by selling those.
  • Also if you have the time/patience, Norberto has on his list plans for eventually developing replacements for both the backplane and front panel boards, at which point we’ll have “modern” equivalents of all of Les’ original boards.
  • If you decide to go ahead and order some of the boards from Les’ design you could see if there is interest here in a group purchase so that $300 for ten boards becomes only $30 out of your pocket.
  • As for a redesign of the front panel to use 1” alphanumeric LEDs – certainly cool if you feel up to it but sounds, to me, like a pretty significant redesign of the front panel and would definitely require a custom cabinet or at least significant modification to an existing H8 bezel.

 

Sorry I can’t help you with the Gerber issue but others here might be able to…

 

Good luck

 

  • Glenn

 

 

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Norberto Collado

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Feb 1, 2021, 12:17:05 PM2/1/21
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To open Les’ gerber files you will need an older version; Kicad_stable_2013…. I think trying to buy an H8 on eBay will be the prefer method as suggested.

 

https://kicad-downloads.s3.cern.ch/index.html?prefix=archive/

 

Graphical user interface, text, application Description automatically generated

 

Norberto

Steven Feinsmith

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Feb 1, 2021, 9:00:09 PM2/1/21
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I removed my latest KiCAD and reloaded the old version. I ran it, and it works fine, but still not able to open Les Bird files for the KICAD at all. Even I replaced Eagle with the old version and failed. I believe the files posted on SEHBC were neither corrupted nor missing files. Honestly, I was disappointed for not able to try order to PCBWAY. They will cost much cheaper. I still wonder how many SEHBC members want to have the Les Bird boards plus your designed boards.

The problem I assume there is no Gerber file from the KiCAD. There should have several files to order the PCB. The SEBHC showed "KiCAD files, opened and there were mix files with one KICAD, several files for Eagle and rest for Pentatonix.

I tried to contact Les Bird, but I have not heard from him.

Thank you,
Steven

To view this discussion on the web visit https://groups.google.com/d/msgid/sebhc/5EAE3EAD-9F2B-42AE-8452-723E7335D4DF%40koyado.com.

Norberto Collado

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Feb 1, 2021, 9:13:20 PM2/1/21
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Send me the link to the Gerber file that you cannot open as I have “Kicad_stable_2013” in my laptop.

 

Norberto

Steven Feinsmith

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Feb 1, 2021, 9:29:26 PM2/1/21
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Here is a link as requested, https://sebhc.github.io/sebhc/pcbs/LesBird_KiCad_Projects.zip

My goal is to get the backplane and front panel PCBs. The rest will be from you. I wonder what happened to Les Bird? I have not seen his conversation lately.

Thanks,
Steven

To view this discussion on the web visit https://groups.google.com/d/msgid/sebhc/90F92A48-FB96-429B-9431-03183D6FCEF1%40koyado.com.

Glenn Roberts

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Feb 1, 2021, 10:11:31 PM2/1/21
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Agree backplane and front panel boards are the most useful and there may be interest in a group purchase. Hope you can find the right combination of software to get things working.

 

Les is around.  I’m sure he’ll check in at some point…

 

  • Glenn

 

 

image001.png

Steven Feinsmith

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Feb 1, 2021, 10:13:24 PM2/1/21
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I have to save money from my social security retirement until I have up to $1500 to purchase Heathkit H8. I like to build the custom H8 with plexiglass instead of metal. I have tools and almost finish my 3D engrave set. I wish that I have a CDC mill machine to create left and right sides. The cooling fan s will be on both sides at half-speed to minimize noise. The rear end will use the ATX power supply as I have over 15 unused ATX power supplies on my shelf. I like to use 2.5" SSD instead of HDD. It is one of my long time dream to build it. I may use Raspberry Pi contained Linux operating system to link with the Internet. I also have a Zenith ZF110 computer that I acquired from former Navy engineering. I will create a link with the Raspberry Pi for file transfer.

My problem that over 95% of the software I acquired from Heathkit/Zenith/S100 companies was gone along with the documentation binders.

I also a member of S100computers as I purchased many S100 boards for a long time. But, I have one board for the H8 and one board for the H89. I assume it was my fault for not join the SEBHC several years earlier. I believe the SEBHC should have stock of H8 and H89 boards. I am not a master of KiCAD software. I need files for the library on both H8 and H89 templates.

I will be 70 years old within few months this year. I know that I have not much left in my life after had an unexpected marital status a few years ago included my health situation. I am alone and stay at home for last March due to the pandemic incident. I enjoy working with Heathkit/Zenith and S100 plus electronic as a hobby. I hope to have an H8 along with my H89 and ZF110 up and running again before I get a call home.

Thank you,
Steven

To view this discussion on the web visit https://groups.google.com/d/msgid/sebhc/008201d6f8b2%24b74778f0%2425d66ad0%24%40gmail.com.

norberto...@koyado.com

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Feb 2, 2021, 4:49:00 AM2/2/21
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The link that you provided worked on my system… I will suggest to wait at least 2 to 4 weeks as I’m planning to order 4-pcs of the H8 backplane. I can share with you one of the boards.

 

On the H8 front panel you should wait as I’m making changes to it.

 

Thanks,

Norberto

 

image001.png
image002.png

Steven Feinsmith

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Feb 2, 2021, 7:25:24 AM2/2/21
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May I suggest you consider adding terminals for all volts to allow users to hook up to measure the current-voltage reading from the backplane? I forward to hear from you about the backplane planning.

Thank you very much,
Steven

To view this discussion on the web visit https://groups.google.com/d/msgid/sebhc/000001d6f948%24a02fb150%24e08f13f0%24%40koyado.com.

George Farris

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Feb 2, 2021, 1:22:57 PM2/2/21
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I am also interested in a backplane.

George


On Tue, 2021-02-02 at 01:48 -0800, norberto...@koyado.com wrote:
> The link that you provided worked on my system… I will suggest to
> wait at least 2 to 4 weeks as I’m planning to order 4-pcs of the H8
> backplane. I can share with you one of the boards.
>  
> On the H8 front panel you should wait as I’m making changes to it.
>  
> Thanks,
> Norberto
>  
>  
> > > Graphical user interface, text, application
> > >
> > > Description automatically generated
> > >  
> > > Norberto
> > >  
> > > From: "se...@googlegroups.com" <se...@googlegroups.com> on behalf
> > > of Glenn Roberts <glenn.f...@gmail.com>
> > > Reply-To: "se...@googlegroups.com" <se...@googlegroups.com>
> > > Date: Monday, February 1, 2021 at 7:55 AM
> > > To: "se...@googlegroups.com" <se...@googlegroups.com>
> > > Subject: RE: [sebhc] PCB for Heathkit H8 Computer
> > >  
> > > Steven: I know you’ve been trying to reestablish your H8
> > > capability ever since the unfortunate theft of your old
> > > equipment. For what it’s worth I offer a few thoughts.
> > >  
> > >  * It sounds like you are considering rolling your own from
> > > “scratch” including a custom chassis?  Perhaps something like
> > > Terry Gulczynski did?
> > > https://sebhc.github.io/sebhc/memberphotos.html?  That would be a
> > > very interesting endeavor!
> > >  * Regardless of your approach this will cost money.  I think you
> > > should budget $1000 to get a system up and running whether you do
> > > it all from scratch or by starting with an eBay find.
> > >  * If your heart isn’t into doing the 100% from scratch approach,
> > > consider starting with something from eBay and
> > > repairing/improving..  there’s a nice system out there now that I
> > > bet will go for close to $1,000 (maybe more!?)  by the time
> > > bidding is over:
> > > https://www.ebay.com/itm/Vintage-Heathkit-H8-computer-with-floppy-drive-cabinet-and-3-x-5-Floppy-Drives/303862878063
> > >  * While it would be cool to build Les’ boards from 2009 there
> > > are more modern boards you could consider.  If it were me I’d get
> > > as plain an H8 as possible from eBay – that gives you the
> > > chassis, power supply, backplane and front panel, then enhance it
> > > with some of Norberto’s latest designs.  With just two of his
> > > boards (the Z80 CPU/serial/USB/RAM/RTC combo and the H37/67/17
> > > I/O board) you can have a very complete and powerful system!  If
> > > your eBay purchase included boards you don’t need you could
> > > offset your costs by selling those.
> > >  * Also if you have the time/patience, Norberto has on his list
> > > plans for eventually developing replacements for both the
> > > backplane and front panel boards, at which point we’ll have
> > > “modern” equivalents of all of Les’ original boards.
> > >  * If you decide to go ahead and order some of the boards from
> > > Les’ design you could see if there is interest here in a group
> > > purchase so that $300 for ten boards becomes only $30 out of your
> > > pocket.
> > >  * As for a redesign of the front panel to use 1” alphanumeric
> > > LEDs – certainly cool if you feel up to it but sounds, to me,
> > > like a pretty significant redesign of the front panel and would
> > > definitely require a custom cabinet or at least significant
> > > modification to an existing H8 bezel.
> > >  
> > > Sorry I can’t help you with the Gerber issue but others here
> > > might be able to…
> > >  
> > > Good luck
> > >  
> > >  * Glenn
> > > https://groups.google.com/d/msgid/sebhc/008201d6f8b2%24b74778f0%2425d66ad0%24%40gmail.com
> > > .
> > > --
> > > You received this message because you are subscribed to the
> > > Google Groups "SEBHC" group.
> > > To unsubscribe from this group and stop receiving emails from it,
> > > send an email to sebhc+un...@googlegroups.com.
> > > To view this discussion on the web visit
> > > https://groups.google.com/d/msgid/sebhc/5EAE3EAD-9F2B-42AE-8452-723E7335D4DF%40koyado.com
> > > .
> > --
> > You received this message because you are subscribed to the Google
> > Groups "SEBHC" group.
> > To unsubscribe from this group and stop receiving emails from it,
> > send an email to sebhc+un...@googlegroups.com.
> > To view this discussion on the web visit
> > https://groups.google.com/d/msgid/sebhc/CAGJMgmWTQ9-aXTFGNokfmnWTQSr6CDH8HyZLyM7ij-KEz%3D3u1g%40mail.gmail.com
> > .
> > --
> > You received this message because you are subscribed to the Google
> > Groups "SEBHC" group.
> > To unsubscribe from this group and stop receiving emails from it,
> > send an email to sebhc+un...@googlegroups.com.
> > To view this discussion on the web visit
> > https://groups.google.com/d/msgid/sebhc/90F92A48-FB96-429B-9431-03183D6FCEF1%40koyado.com
> > .

norberto.collado koyado.com

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Feb 2, 2021, 2:18:00 PM2/2/21
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Here is a copy of the new H8 backplane. I only added jumpers for the +5V STB and +3.3 volts for the smaller cards. Also it supports the PC switch. No plans to add any other headers.



From: 'George Farris' via SEBHC <se...@googlegroups.com>
Sent: Tuesday, February 2, 2021 10:22 AM
To: se...@googlegroups.com <se...@googlegroups.com>
New-H8-backplane.PNG

Glenn Roberts

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Feb 2, 2021, 4:48:12 PM2/2/21
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Nice. didn’t realize you were this close to finalizing.  Don’t know if Todd’s willing to continue to honcho board orders once you’re ready to order them,  but that’s worked well from the group’s perspective.

image001.png

Todd Goodman

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Feb 2, 2021, 5:27:03 PM2/2/21
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Hi Glenn, Norberto and group,

I'm certainly willing to make bulk purchases for the group (and to keep some on hand for any future requests) once ready for this and any other boards as well.

Todd

norberto.collado koyado.com

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Feb 2, 2021, 5:27:46 PM2/2/21
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I need to order a few boards to check for any layout mistakes or signals issues before giving them to Todd. I do not want Todd to order boards that will not work on power-on. I do not like re-works and I just need to do another sanity check on such backplane before ordering some boards to test them o.

Norberto

Sent: Tuesday, February 2, 2021 1:48 PM
To: se...@googlegroups.com <se...@googlegroups.com>

s shumaker

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Feb 2, 2021, 10:11:59 PM2/2/21
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When will you start building a list for this?

Steve

Norberto Collado

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Feb 2, 2021, 11:32:58 PM2/2/21
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Todd will take care of the list once I approved the Gerber files for production. Also I’m debating on using the same pads as in the original design. What do you think?

 

 

Norberto

Norberto Collado

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Feb 3, 2021, 3:10:51 AM2/3/21
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Here is a better picture and schematics.

 

Norberto

H8-BCK-DUAL-CPUS.png
H8_BP_DUAL_CPU_Schematics.pdf

Steven Feinsmith

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Feb 3, 2021, 4:34:38 AM2/3/21
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Norberto and Todd (Goodman) are very reliable and trustworthy. Just give them time and patience.

Thanks,
Steven

To view this discussion on the web visit https://groups.google.com/d/msgid/sebhc/aafe2e85-382b-9131-7646-86064f69d5d0%40att.net.

Glenn Roberts

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Feb 3, 2021, 8:39:41 AM2/3/21
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I think I agree, not sure what your alternative would be (smaller circular ones?).  these presumably were elongated to allow for stronger solder bond due to stress from inserting/removing cards…

image003.png
image004.png

Norberto Collado

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Feb 16, 2021, 2:58:53 AM2/16/21
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After reviewing the H8 backplane against the Trionyx backplane, I decided to use the same pads rather than the round pads. So give me time as I need to re-wired everything again.

 

Trionyx pads:

 

A close - up of a computer Description automatically generated with low confidence

 

Thanks,

Norberto

norberto.collado koyado.com

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Feb 16, 2021, 5:22:20 PM2/16/21
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Big difference when comparing both pads... Does anyone have an H8 original backplane not using anymore that I could borrow to check on hole alignment?



From: se...@googlegroups.com <se...@googlegroups.com> on behalf of Norberto Collado <norberto...@koyado.com>
Sent: Monday, February 15, 2021 11:58 PM

norberto.collado koyado.com

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Feb 17, 2021, 10:56:50 PM2/17/21
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With the new pads, the new H8 backplane looks much, much better. I would like to borrow the original H8 backplane before ordering to verify hole alignment if anyone has a spare outside the system. The clock "02" signal is placed on side 1 as the others are on side 2. The jumpers are to break the backplane into two pieces, so that we can have two CPUs on same chassis if needed. Only Z80 V3.x will work on such configuration. One CPU could boot from the H8-CF card while the other from the Z67-IDE+ card. As I have two Z80 V3.x cards, I would like to use both of them, rather than having one on the shelf and the other one in use. 


From: se...@googlegroups.com <se...@googlegroups.com> on behalf of norberto.collado koyado.com <norberto...@koyado.com>
Sent: Tuesday, February 16, 2021 2:22 PM

To: se...@googlegroups.com <se...@googlegroups.com>
Subject: Re: [sebhc] PCB for Heathkit H8 Computer
Big difference when comparing both pads... Does anyone have an H8 original backplane not using anymore that I could borrow to check on hole alignment?



From: se...@googlegroups.com <se...@googlegroups.com> on behalf of Norberto Collado <norberto...@koyado.com>
Sent: Monday, February 15, 2021 11:58 PM
To: se...@googlegroups.com <se...@googlegroups.com>
Subject: Re: [sebhc] PCB for Heathkit H8 Computer
 

After reviewing the H8 backplane against the Trionyx backplane, I decided to use the same pads rather than the round pads. So, give me time as I need to re-wire everything again.

George Farris

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Feb 18, 2021, 12:22:46 AM2/18/21
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Hi Norberto,

If you can't find one in the US I have one here in BC.  I could send it to you.

George

Glenn Roberts

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Feb 18, 2021, 2:58:44 AM2/18/21
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I will check. I might have one...

Sent from my iPad

On Feb 18, 2021, at 12:22 AM, 'George Farris' via SEBHC <se...@googlegroups.com> wrote:


Hi Norberto,

If you can't find one in the US I have one here in BC.  I could send it to you.

George


On Thu, 2021-02-18 at 03:56 +0000, norberto.collado koyado.com wrote:
With the new pads, the new H8 backplane looks much, much better. I would like to borrow the original H8 backplane before ordering to verify hole alignment if anyone has a spare outside the system. The clock "02" signal is placed on side 1 as the others are on side 2. The jumpers are to break the backplane into two pieces, so that we can have two CPUs on same chassis if needed. Only Z80 V3.x will work on such configuration. One CPU could boot from the H8-CF card while the other from the Z67-IDE+ card. As I have two Z80 V3.x cards, I would like to use both of them, rather than having one on the shelf and the other one in use. 

<image.png>

From: se...@googlegroups.com <se...@googlegroups.com> on behalf of norberto.collado koyado.com <norberto...@koyado.com>
Sent: Tuesday, February 16, 2021 2:22 PM
To: se...@googlegroups.com <se...@googlegroups.com>
Subject: Re: [sebhc] PCB for Heathkit H8 Computer
 
Big difference when comparing both pads... Does anyone have an H8 original backplane not using anymore that I could borrow to check on hole alignment?

<image.png>


From: se...@googlegroups.com <se...@googlegroups.com> on behalf of Norberto Collado <norberto...@koyado.com>
Sent: Monday, February 15, 2021 11:58 PM
To: se...@googlegroups.com <se...@googlegroups.com>
Subject: Re: [sebhc] PCB for Heathkit H8 Computer
 

After reviewing the H8 backplane against the Trionyx backplane, I decided to use the same pads rather than the round pads. So, give me time as I need to re-wire everything again.

 

Trionyx pads:

 

<image001.jpg>

 

Thanks,

Norberto

 

From: "se...@googlegroups.com" <se...@googlegroups.com> on behalf of "norberto.collado koyado.com" <norberto...@koyado.com>
Reply-To: "se...@googlegroups.com" <se...@googlegroups.com>
Date: Tuesday, February 2, 2021 at 11:17 AM
To: "se...@googlegroups.com" <se...@googlegroups.com>
Subject: Re: [sebhc] PCB for Heathkit H8 Computer

 

Here is a copy of the new H8 backplane. I only added jumpers for the +5V STB and +3.3 volts for the smaller cards. Also it supports the PC switch. No plans to add any other headers.

 

<image002.png>

glenn.f...@gmail.com

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Feb 18, 2021, 10:52:26 AM2/18/21
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Norberto: I have an original backplane (85-1936-1) I can send you. It has the pins and parts mounted on it (not a blank board) – will that serve your purpose?

image003.png
image004.jpg
image005.png

glenn.f...@gmail.com

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Feb 18, 2021, 10:58:15 AM2/18/21
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Awesome!  One possible concern: it looks like the mounting screws could accidentally short the 5V to ground if they cut into the foils.  Could use fiber washers or nylon screws I suppose… but that’s not ideal (sooner or later someone will “forget” and put in a metal screw and lockwasher).

 

image003.png
image004.png
image005.png
image008.png
image001.jpg

Norberto Collado

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Feb 18, 2021, 11:33:18 AM2/18/21
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Hello Glenn,

 

That will help as I just need to verify on side #2 the measurements.

 

Thanks George for the offer as Glenn is much closer.

 

Norberto

Norberto Collado

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Feb 18, 2021, 11:38:52 AM2/18/21
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Sure, I will take a look at that. As I have the 3-pin header on the top, perhaps I can re-route power on side 1. I’m also concerned on the thickness of the foil might be an issue and become a fuse when using older boards.

 

Thanks,

Norberto

norberto.collado koyado.com

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Feb 18, 2021, 2:04:24 PM2/18/21
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I think this is much better. 


Thanks for the feedback!

Norberto



Sent: Thursday, February 18, 2021 8:38 AM
To: se...@googlegroups.com <se...@googlegroups.com>

Glenn Roberts

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Feb 18, 2021, 4:40:43 PM2/18/21
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Beautiful!

Sent from my iPad

On Feb 18, 2021, at 2:04 PM, norberto.collado koyado.com <norberto...@koyado.com> wrote:


I think this is much better. 


Thanks for the feedback!

Norberto

<image.png>


From: se...@googlegroups.com <se...@googlegroups.com> on behalf of Norberto Collado <norberto...@koyado.com>
Sent: Thursday, February 18, 2021 8:38 AM
To: se...@googlegroups.com <se...@googlegroups.com>
Subject: Re: [sebhc] PCB for Heathkit H8 Computer
 

Sure, I will take a look at that. As I have the 3-pin header on the top, perhaps I can re-route power on side 1. I’m also concerned on the thickness of the foil might be an issue and become a fuse when using older boards.

 

Thanks,

Norberto

 

From: "se...@googlegroups.com" <se...@googlegroups.com> on behalf of <glenn.f...@gmail.com>
Reply-To: "se...@googlegroups.com" <se...@googlegroups.com>
Date: Thursday, February 18, 2021 at 7:57 AM
To: "se...@googlegroups.com" <se...@googlegroups.com>
Subject: RE: [sebhc] PCB for Heathkit H8 Computer

 

Awesome!  One possible concern: it looks like the mounting screws could accidentally short the 5V to ground if they cut into the foils.  Could use fiber washers or nylon screws I suppose… but that’s not ideal (sooner or later someone will “forget” and put in a metal screw and lockwasher).

 

<image001.png>

 

From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of norberto.collado koyado.com
Sent: Wednesday, February 17, 2021 10:57 PM
To: se...@googlegroups.com
Subject: Re: [sebhc] PCB for Heathkit H8 Computer

 

With the new pads, the new H8 backplane looks much, much better. I would like to borrow the original H8 backplane before ordering to verify hole alignment if anyone has a spare outside the system. The clock "02" signal is placed on side 1 as the others are on side 2. The jumpers are to break the backplane into two pieces, so that we can have two CPUs on same chassis if needed. Only Z80 V3.x will work on such configuration. One CPU could boot from the H8-CF card while the other from the Z67-IDE+ card. As I have two Z80 V3.x cards, I would like to use both of them, rather than having one on the shelf and the other one in use. 

 

<image002.png>

From: se...@googlegroups.com <se...@googlegroups.com> on behalf of norberto.collado koyado.com <norberto...@koyado.com>
Sent: Tuesday, February 16, 2021 2:22 PM
To: se...@googlegroups.com <se...@googlegroups.com>
Subject: Re: [sebhc] PCB for Heathkit H8 Computer

 

Big difference when comparing both pads... Does anyone have an H8 original backplane not using anymore that I could borrow to check on hole alignment?

 

<image003.png>

 

From: se...@googlegroups.com <se...@googlegroups.com> on behalf of Norberto Collado <norberto...@koyado.com>
Sent: Monday, February 15, 2021 11:58 PM
To: se...@googlegroups.com <se...@googlegroups.com>
Subject: Re: [sebhc] PCB for Heathkit H8 Computer

 

After reviewing the H8 backplane against the Trionyx backplane, I decided to use the same pads rather than the round pads. So, give me time as I need to re-wire everything again.

 

Trionyx pads:

 

<image004.jpg>

 

Thanks,

Norberto

 

From: "se...@googlegroups.com" <se...@googlegroups.com> on behalf of "norberto.collado koyado.com" <norberto...@koyado.com>
Reply-To: "se...@googlegroups.com" <se...@googlegroups.com>
Date: Tuesday, February 2, 2021 at 11:17 AM
To: "se...@googlegroups.com" <se...@googlegroups.com>
Subject: Re: [sebhc] PCB for Heathkit H8 Computer

 

Here is a copy of the new H8 backplane. I only added jumpers for the +5V STB and +3.3 volts for the smaller cards. Also it supports the PC switch. No plans to add any other headers.

 

<image005.png>

norberto.collado koyado.com

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Feb 18, 2021, 7:46:21 PM2/18/21
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This should be much better!



From: se...@googlegroups.com <se...@googlegroups.com> on behalf of Glenn Roberts <glenn.f...@gmail.com>
Sent: Thursday, February 18, 2021 1:40 PM

Norberto Collado

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Feb 24, 2021, 6:55:41 PM2/24/21
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Hopefully Glenn’s H8 backplane should be here this weekend to verify measurements against the new H8 backplane, before ordering a prototype to check it out.

 

In the meantime I bought one of the SFX Power Supplies to verify the PC switch On/Off feature along with other features. This power supply is only to support the new H8 boards. If you need to support the older H8 boards you will need to either update the regulators or buy the “Well PSU’s” as previously stated by Dave McGuire.

 

I received today the ”123-GM-0550” SFX and it is very, very small. At 5V it packs about 20A and that can burn out the backplane if by mistake something shorts out. I think I shall add a 6A PPTC (will trip @ 10A) in series with the +5v power rail. For 3.3v will limit as well.

 

A calculator and a monitor on a desk Description automatically generated with low confidence

Glenn Roberts

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Feb 24, 2021, 9:49:01 PM2/24/21
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Can’t remember the last time I got a “two day” USPS delivery in anything like two days.  Maybe last fall?  Right now your package is showing the dreaded status : “Your package will arrive later than expected, but is still on its way. It is currently in transit to the next facility” which seems to mean “your package is stuck in a truck or a warehouse and we’ll probably find it in a week or two…”

 

Let’s hope for the best.

 

Will be very interested in following your use of the EVGA SFX power supply.  On Rusty I didn’t use your 555 timer circuit but instead just wired the existing H8 power switch across the appropriate two terminals on the power supply cable.  have you given any thought to where to locate the pushbutton for the 555 on/off power switch?  Presumably on the back somewhere rather than drill into the front panel.

image003.jpg

Norberto Collado

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Feb 27, 2021, 1:47:09 AM2/27/21
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Have you given any thought to where to locate the pushbutton for the 555 on/off power switch? 

 

I did brainstorm this before with Terry G. and concluded that I need to find a round switch that will fit the fuse hole. The fuse will no longer be needed if using a PC power supply.

 

If anyone knows about a pushbutton that is round and that will fit the fuse hole, just let me know.

Norberto Collado

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Feb 27, 2021, 2:13:25 AM2/27/21
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Received yesterday Glenn’ original H8 backplane. Did a quick check and holes do not aligned properly and the 25 pin headers are shift up by one pad. A lot of measurements to do to have an exact copy.

 

This is going to take a while to fix and will need to re-route again the whole board.

 

A close - up of a circuit board Description automatically generated with low confidence

 

 

Norberto

Norberto Collado

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Feb 27, 2021, 3:23:44 AM2/27/21
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I think the fuse hole diameter is 12mm, so this momentary switch should be fine.

 

https://www.amazon.com/gp/product/B07HFXNRQJ/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

 

Norberto

glenn.f...@gmail.com

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Feb 27, 2021, 9:41:38 AM2/27/21
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Resending (meant to CC sebhc originally…)

 

 

From: glenn.f...@gmail.com <glenn.f...@gmail.com>
Sent: Saturday, February 27, 2021 9:39 AM
To: 'Norberto Collado' <norberto...@koyado.com>
Subject: RE: [sebhc] PCB for Heathkit H8 Computer

 

I have not seen any issues from this difference in alignment, in fact I never noticed it before.  All of the boards in this system, however, are new (either “Les Bird” or “Norberto” creations) so can’t say if there’s an issue with legacy boards.  It seems the full size boards do go “downhill” slightly as they run from the backplane to the left of the chassis.  One possible benefit is there is a little more room under the card, e.g. to pass ribbon cables between boards.

 

The “Heathkit” backplane has room for 7 official expansion boards (positions 3-9, 1 being used by the front panel and 2 by the CPU) and has a 10’th slot that only had one “officially sanctioned” use that I know of – the HA-8-8 “extended configuration” board. The “Les” board actually has half-position locations which I have used for some of the smaller boards on occasion.  The “Heath”  slot-10 position is actually slot “9-1/2” on Les’ layout and he adds an actual Slot 10, spaced evenly with the others.  This would not be usable in a standard H8 chassis due to conflict with the metal housing for the capacitor, however in an “H8-2000” configuration using a PC power supply there is potentially room to use this 10’th position, depending on where the power supply is installed.  On Rusty I have my real time clock/calendar board installed there

 

https://photos.app.goo.gl/sVARW89Wf7dDXMUw7

 

In general I think most of the issues in the past with lack of backplane slots were due to memory boards.  Early on many of us had multiple RAM boards, buying a little bit at a time to expand our systems (16K was $395 – that’s the equivalent to over $1,200 today!). It may be safe to assume most people now use only at most one slot for RAM, maybe none (e.g. for the new CPU boards with 64K on them). This helps greatly with slot contention.

 

From: Norberto Collado <norberto...@koyado.com>
Sent: Saturday, February 27, 2021 1:48 AM
To: Glenn Roberts <glenn.f...@gmail.com>
Subject: Re: [sebhc] PCB for Heathkit H8 Computer

 

Thanks Glenn for sending the board. I see that the backplane holes does not aligned properly and the pads are shifted up by one pin. I checked against Les’ V1.4 backplane and same issue. A lot of clean-up to do to create a exact match with the older H8 backplane. See attached picture. I’m very happy that you shared such backplane with me.

 

You do have a Les’ backplane V1.4; correct? Any issues with alignment? Also I see that he added at the end of the backplane another header and I do not think there is space for any board there. I will double check on my system.

 

Thanks a lot!

Norberto

 

Norberto Collado

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Feb 27, 2021, 6:33:22 PM2/27/21
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Thank you for checking this out and for the picture. Can you send me a picture on how you wire AC into the PC power supply?

 

Norberto

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glenn.f...@gmail.com

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Feb 28, 2021, 9:42:08 PM2/28/21
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I’m afraid I never did anything fancy here.  I just snaked the power cord through the open hole where the aux power outlet used to be.  It would be easy enough to add a cord restrainer and put the cord through the original hole, but that would entail making a splice. 

 

https://photos.app.goo.gl/8KY5UUwpxExU6BxC7

 

a more professional looking approach would be to reinstall the aux power outlet and run the cord through the original cord hole (with a retainer), then make the splice at the power outlet.  The fuse holder hole could then be used for the power push button.  This would avoid leaving any gaping holes in the back.

 

From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of Norberto Collado

Steven Feinsmith

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Feb 28, 2021, 10:12:58 PM2/28/21
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I appreciate everyone helping Norberto with his backplane project. It takes time to refine and final prototype before sending it out for PCB manufacturing.

I reviewed previous messages about the backplane. I realized an important feature was not available on the backplane since Heathkit created it. We need to put a termination circuit that can be used from S100computers to implement the H8 backplane. I strongly encourage you to consider adding the termination feature then you can compare the difference.

See: http://www.s100computers.com/My%20System%20Pages/Terminator%20Board/Bus%20Terminator%20Board.htm

Secondly, I strongly encourage you to put a terminal for each voltage and hook it up with a digital voltage/ammeter device to show how much current from the power supply before entering the power buses. If anyone is not interested, this feature can place a metal jumper. One of my old prototype S-100 chassis has multi-panels to show the voltage and ampere reading. It is useful for work on the prototype boards to measure the power requirement.

Thank you very much for your consideration,
Steven

glenn.f...@gmail.com

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Mar 1, 2021, 12:19:56 PM3/1/21
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My two cents:

 

I understand the reason for bus termination but, just an observation, I’m not aware of any significant noise/signal reflection issues without it.  I run multiple systems at varying frequencies up to 10Mhz and have not had any problems.  Perhaps if we tried to push to 16 or 20Mhz this would become an issue? I believe the Trionyx board had accommodation for passive termination?  I’m sure Norberto gave this some consideration and (perhaps?) decided its not a critical issue?  I suppose one could construct a termination board and plug it into the bus??

 

Current measurement would be a nice to have but I’m concerned about how that would complicate the board layout?  Plus not really an issue for modern boards.  Maybe for some of the old monster RAM boards (e.g. Godbout, Trionyx) that sucked up power…  the mfg. usually gave a spec. on the power draw so it wasn’t that big a deal to make sure you weren’t overloading.  With today’s lower power chips and switching regulators power and heat just aren’t that big a concern.

 

image001.jpg

Norberto Collado

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Mar 1, 2021, 1:16:15 PM3/1/21
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The only concern that I have is with the H8 extended board that is not buffered and will cause bus timing issues. It is a great idea but a bad implementation. The fix will be to buffer all the signals on such board so that it shows as another H8 board. It is on the TO-DO list. Other than that, the H8 is running fine even at 16MHz, which I tested already with the CF controller card.

 

http://koyado.com/Heathkit/H8_Extender_Board.html

 

On the new backplane, I’m adding PTC fuses, to limit the current as the PC Power Supplies are very powerful in terms of current. Do not install the PTC fuse and connect your shunt resistor to monitor Voltage and current.

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