Enjoyed the ShadowTron video…
In there he discusses the 25-pin Molex edge connectors and how a while back some of us (not me unfortunately) bought up some stock. Those Molex connectors are now listed (at least by Mouser) as “obsolete”
Verical says they have 62 in stock with minimum order quantity of 7. $5.18 each. I’ve not dealt with this vendor before.
The edge connectors that Norberto usually recommends are a Samtec product (BCS-125-L-S-HE). Currently both DigiKey and Mouser are out of stock with 8-10 week lead time ☹
Sager has 278 in stock @$4.59 per unit.
Also Powell at same price
Those are two vendors that I am also not familiar with…
From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of norberto...@koyado.com
Sent: Thursday, June 03, 2021 2:40 AM
To: se...@googlegroups.com
Subject: RE: [sebhc] H8 8080A/Z80 64K RAM ORG0 BRD
Shadow Tron documented this 8080A/Z80 64K board in detail. He created 6 chapters which I enjoyed watching a lot. I need to add a link to my website.
https://www.youtube.com/watch?v=xpvd9NF3iq0 - chapter 1.
On this board the team rally behind it and it is well documented. I thank everyone that helped.
Norberto
From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of Mitchell Smith
Sent: Wednesday, June 2, 2021 10:35 PM
To: SEBHC <se...@googlegroups.com>
Subject: Re: [sebhc] H8 8080A/Z80 64K RAM ORG0 BRD
I watched a couple youtube videos from Shadow Tron. He built one of these. I love the memory backup battery. Great feature.
On Wednesday, June 2, 2021 at 12:06:23 PM UTC-7 Norby wrote:
The beauty of this board is that it works with any H8 monitor and CPU’s (8080A, Z80). As I can select any memory region, it can be used to debug older memory boards. For example, I select the first 8K region for this board, skip another 8K region, and enabled the older memory boars above this region to debug it. Then I use the H8 front panel monitor to debug such older memory board.
This board works fine up to 10MHz.
Norberto
From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of Glenn Roberts
Sent: Wednesday, June 2, 2021 2:42 AM
To: se...@googlegroups.com
Subject: Re: [sebhc] H8 8080A/Z80 64K RAM ORG0 BRD
This is a nice board. I didn’t appreciate the value of the on-board battery backup until I started using this with the H-8-5 serial port and front panel load and dump functions. This lets you load programs into RAM at any location and run them from the front panel by setting the PC and hitting GO. No OS or boot process required. Let’s you load up multiple programs and quickly run them, e.g. for demo purposes and at computer fests.
Sent from my iPad
On Jun 2, 2021, at 1:23 AM, Mitchell Smith <kb3...@gmail.com> wrote:
Yes, that's the one.
Just to confirm, I have a regular H8 with the 8080 CPU. No modifications.
Also looking for an extender board if you have one of those available.
Thanks a bunch!
Mitch
On Tuesday, June 1, 2021 at 9:07:27 PM UTC-7 Norby wrote:
Yes, I do have some spares.
You are looking for this one; correct?
Thanks,
Norberto
From: se...@googlegroups.com <se...@googlegroups.com> on behalf of Mitchell Smith <kb3...@gmail.com>
Sent: Tuesday, June 1, 2021 8:05 PM
To: SEBHC <se...@googlegroups.com>
Subject: [sebhc] H8 8080A/Z80 64K RAM ORG0 BRD
I'm thinking about building the H8 8080A/Z80 64K RAM ORG0 board.
Does anyone have a PCB available for sale?
If not I may place an order with OurPCB.
Thanks!
Mitch
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And Terry Smedley showed me an example where he used multiple of the smaller Molex units (which are still available) . see attached.
Terry says Molex part numbers: 22-16-2xx1, xx=number of positions
Digikey stocks 4,5,6,10 position
Mouser stocks others
At the risk of beating a dead horse…
The Molex connectors ending in ‘0’ are probably fine for our purpose, slightly thinner gold coating. But ½ the cost or less. So to build up a 51-positoin edge connector you could, say, do 3 16-pin connectors and a 3-pin one, or 3 15’s and a 6. Then use a Molex polarizing key to block the position in the middle (handy for preventing power supply burnout from mis-aligned card!)
From Mouser:
3x15 pins: 538-22-16-2150 $2.10 $6.30
1x 6 pins: 538-22-16-2061 $2.39 $2.39
TOTAL/board: $8.69
Or
3x 16 pins: 538-22-16-2160 $2.50 $7.50
1x 3 pins: 538-22-16-2031 $1.12 $1.12
TOTAL/board: $8.62
I believe the connector keys are Mouser # 538-15-04-0219. They have plenty of stock on all of the above components.
Using the connector key to block the center hole is a little more elegant than Gorilla-gluing a shorting block in between the Samtec connectors 😊
Thanks to Terry Smedley for suggesting this approach.
Or blame me. I just received 4 of them from Mouser which, at the time I ordered, depleted their stock ☹ I wasn’t observant enough in my previous DigiKey order and didn’t realize those were back ordered, so some day 6-8 weeks from now I should have more !
The Samtec edge connector should be mounted as close to the edge of the board as possible with the shrouded hole openings toward the edge. The holes on the back of the connector are open showing the metal contacts. I haven’t seen a picture of an assembled 4.0 board yet but will gladly share mine once it’s complete (still waiting on some components).
Norberto has a picture of the rev 3 board which shows the edge connector installed:
http://koyado.com/Heathkit/H8-Z80-64K-RTC-ORG0-V3.html
Both the 3.x and 4.x boards have accommodations to install an optional header row behind the edge connector. I’m guessing this is to simplify testing and signal measurement (?) or I suppose could be used in the future to support a piggyback board?
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On Jun 7, 2021, at 9:45 PM, Terry Smedley <terry....@gmail.com> wrote:
Completed v4 CPU. Molex 22-16-2251 bus connectors. You can also see an 8-pin header installed to provide access to the IRQ lines, as Glenn noted. Low-profile ZIF socket used for the EEPROM. An I2C temperature sensor is attached to the surface of the Z80 CPU.
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<Complete Front DUART.jpg><Complete Front.jpg>
Perhaps a nit but Terry’s photo actually shows the connector 180 degrees opposite of the way I’d recommend install. Here’s the side that should face toward the edge:
And here’s what the back of the connector looks like:
It’s easy to put these in backwards (voice of experience), though I doubt there’s any real problem with it installed that way.
From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of Terry Smedley
Sent: Monday, June 07, 2021 7:40 PM
To: se...@googlegroups.com
Subject: Re: [sebhc] Re: Segue to new topic: Edge connectors
Hi, Geri
Your Samtec connectors should look like this photograph, with two rows of solder pins. They are installed as shown in the top of the photo (not the v4 card, but similar to it). Hope this helps!
Terry
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Beautiful build Terry. the ZIF is a nice touch. Also I note use of machined sockets (good) but dual wipe for the H37 I/O interconnection, which is subject to more frequent connection/disconnection (clever!). Plus as you’ve noted the extra header for access to IRQs.
On the edge connectors I note that Mouser must not sell many (are we the only buyers?) they’re ordering in pretty small quantities:
For Digikey they categorize this as a “value added” item:
“This is a value added item which we custom assemble or package. In most instances we can assemble or package this item specifically for your order and ship it the same day. If you place this item on your order it will show up backordered. We will contact you if we are unable to fulfill your order”
In the past I’ve gotten these right away despite this categorization, but this time I seem to have to wait (and they didn’t contact me ☹ ). I chatted with a help agent at DigiKey and I think I sort of understand. She says they are “put together in the warehouse” and ordered “on demand”. It sounds like they keep shells and contacts in stock and make these up to length based on demand? Perhaps they’re extra busy now? She told me estimated date for my backorder is about 2 weeks… there will be an extra shipping fee for that package.
It looks like you’ve used the Monolithic Power Systems DC-DC converters
My only caveat would be for anyone who wants to power their system with a PC/ATX style power supply I would think there could be an issue as these converters require a minimum input voltage of 6.5V. the Pololu will work with a wider range of input voltages (2 to 16)… but for straight replacement of the 7805 the MPS ones are a good way to go; cool and cheap!
From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of Terry Smedley
Sent: Monday, June 07, 2021 9:36 PM
To: se...@googlegroups.com
Subject: Re: [sebhc] Re: Segue to new topic: Edge connectors
Completed v4 CPU, with and without DUART serial board. Bus connectors are Molex 22-16-2251. Low profile ZIF socket used for EEPROM.
Terry
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Hello Terry,
Can you send me the schematics on how you control the Fans RPM’s?
Thanks,
Norberto
Terry
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On another email thread with Terry, he helped me identify a new 2x25 connector for $3.84 each, which allows to move back the board or to the front depending on space needs between each board. I’m planning to use them for the mini-boards. I will order a few to test out.
3M 6850 series with gold contacts, tin posts: https://www.digikey.com/short/8d458fhv
3M 8550 series with gold contacts, gold posts: https://www.digikey.com/short/p3b3wddf ; more expensive
Thanks,
Norberto
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From: "se...@googlegroups.com" <se...@googlegroups.com> on behalf of Terry Smedley <terry....@gmail.com>
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Date: Monday, June 7, 2021 at 6:45 PM
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Very nice and thank you.
Error! Filename not specified.
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Norberto: would this connector allow the CPU board to be set back a bit in the first slot? With the “classic” front panel (FP) board and the latest Z80 CPU boards there’s really not enough space and I have to waste the first slot by setting the CPU in slot 2… Pretty sure once we have the new front panel there will be a lot more breathing room between the CPU and the FP board? The “rats next” of wire in the original H8 design has always been an issue.
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On the Front Panel board, perhaps we can add an spacer between the board and the bracket that holds the front panel in place. That should give you more clearance between the CPU and the H8 FP.
Norberto
Verical says they have 62 in stock with minimum order quantity of 7. $5.18 each. I’ve not dealt with this vendor before.
To view this discussion on the web visit https://groups.google.com/d/msgid/sebhc/2a27e8a9-047a-4122-9218-bd7db4a2d4afn%40googlegroups.com.
Or do you want me to add another connector to the new H8 backplane to move the CPU board away from the Front panel. I’m almost ready to order the new backplane for testing.
From: norberto...@koyado.com <norberto...@koyado.com>
Sent: Monday, June 21, 2021 10:42 PM
To: 'se...@googlegroups.com' <se...@googlegroups.com>
Subject: RE: [sebhc] Re: Segue to new topic: Edge connectors
On the Front Panel board, perhaps we can add an spacer between the board and the bracket that holds the front panel in place. That should give you more clearance between the CPU and the H8 FP.
Norberto
Verical says they have 62 in stock with minimum order quantity of 7. $5.18 each. I’ve not dealt with this vendor before.
To view this discussion on the web visit https://groups.google.com/d/msgid/sebhc/2a27e8a9-047a-4122-9218-bd7db4a2d4afn%40googlegroups.com.
On Jun 22, 2021, at 2:42 AM, norberto...@koyado.com wrote:
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