New boards in development!

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norberto.collado koyado.com

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Jul 23, 2022, 5:40:53 PMJul 23
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H8-Z5-4 – Cassette Tape

 

  • Thanks to Glenn for sharing with me the original H8-5 board, I was able to verify the timing and also to load H8 original tapes without any issues. I had to re-start the layout from the beginning on this new board. I think I have everything in place and ordered a few boards to test it out.
    • It has the fix to use any 82C51 to upload/download tapes from cassette player. This feature not tested yet.
    • Added 8251 for console with /INT3 support – baud rate selectable
    • Added 16C550 for console with /INT3 support
    • It uses 1.8432 MHz oscillator for better baud rate timing
    • Uses same analog components as in the H8-5 original board
    • Same analog adjustments as in the H8-5 board
    • Better relays to control the cassette recorder/player
    • Added jumpers to make it easy to calibrate
    • Added H8T design, so that it can upload/download from the PC at 1200bps or 9600bps, jumper selectable.
    • It uses DB9 to 10 pin connector cables (Qty: 3-pcs)
    • Overall, same features as in the original H8-5 board + new features added.
    • Link to board picture: http://koyado.com/heathkit/New-H8-Website/download/h8-z5-4side1_view.png

 

 

H8-H67-Z67-IDE Hard Drive

 

  • I took the original H8-Z67-IDE board and refreshed with this full length board. I ordered a few board to check it out.
    • Support up to 10MHz CPU operations. It can be pushed to 16MHz with I/O wait states.
    • Per Douglas feedback, eliminated the 82C55 I/O controller. Now it uses a 74HCT245 bus driver. The FW code should be smaller.
    • It supports 4 drives. It should boot from 0-3 using H8 front panel. This feature not tested yet.
    • It uses IDE CF drives.
    • Will support SD cards with correct IDE adapter.
    • It installs inside the H8
    • Can be installed outside the H8 system in a custom chassis.
    • Added support to use either LCD display or OLED display (same display as in the GoteK drive)
    • Added Rotatory Encoder Module support to select virtual disks.
    • Added I2C support , thanks to Terry S. with the PCA9665N IC.
    • It uses DB9 to 10 pin connector cable (1-pcs)
    • FLASH EEPROM for custom support added
    • Link to board picture: http://koyado.com/heathkit/New-H8-Website/download/h8_z67-dual_ide_side1%20(1).png

 

 

H8/H89-Z67-SDC Hard Drive

 

  • My first attempt to use SD cards to replace the Z67-IDE+ board resulted in very severe timing issues, which I couldn’t fix. I want to thank Terry S and Douglas for their feedback to get the board operational. I scrapped this board and restarted again a new board. I just ordered new pcb’s to give it a second run.
    • Leverage Z67-IDE+ to support SDC flash drives and to eliminate timing issues.
    • It should run at 10MHz or above with CPU I/O wait states.
    • Will support removing/inserting SD cards while power is on.
    • Will support LCD or OLED displays
    • FLASH EEPROM for custom support added
    • Rotatory Encoder module added
    • Each drive partition is 1GB to match SASI specs.
    • Link to board picture: http://koyado.com/heathkit/New-H8-Website/download/z67-sdc-plcc44-scsi-side1-view.png

 

Thanks,

Norberto

 

Steven Hirsch

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Jul 23, 2022, 6:06:06 PMJul 23
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On 7/23/22 17:40, norberto.collado koyado.com wrote:
> H8-Z5-4 – Cassette Tape
>

>
> H8-H67-Z67-IDE Hard Drive
>
>
> H8/H89-Z67-SDC Hard Drive
>

You never fail to amaze, Norberto! Great work.

norberto.collado koyado.com

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Jul 24, 2022, 11:59:33 PMJul 24
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Thanks Steven!

I just got email that boards shipped today. Hopefully they will be on my hands by weekend to build out the H8-Z5-4 board.

Norberto
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Darrell Pelan

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Jul 26, 2022, 10:15:20 AM (13 days ago) Jul 26
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Impressive list of projects!

norberto.collado koyado.com

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Jul 28, 2022, 12:17:22 AM (11 days ago) Jul 28
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Not bad on delivery. I ordered the boards on Saturday and received them today.

I will start the assembly on the new H8-Z5-4 cassette recorder. It should hopefully, if no layout issues, be able to read the original H8 tapes. Once working, I will return the original H8-5 boards back to Glenn.

The other two boards are the new Z67-SDC for the H89/H8 systems and the new H8-Z67-IDE to install inside the H8 system or into a chassis. One uses IDE CF/SD cards and the other one uses ONLY SD cards.

See attached picture.

Norberto
New_H8_Z5-4_Board.jpg

norberto.collado koyado.com

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Jul 30, 2022, 5:57:47 PM (9 days ago) Jul 30
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I'm still working on the build-out of the H8-Z5-4 board. I took a picture to compare against the original board as I did try to make it the same as much possible.

I hope to fire this bay up tomorrow or by next week.

Picture attached!

Thanks,
To view this discussion on the web visit https://groups.google.com/d/msgid/sebhc/SN6PR01MB3855B6CAC872B56CFBA5E0AAF7969%40SN6PR01MB3855.prod.exchangelabs.com.
H8-Z5-4 board.jpg

Glenn Roberts

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Jul 31, 2022, 5:49:50 AM (8 days ago) Jul 31
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Nice! Are the Potter & Brumfiled parts mechanical relays or solid state? Nice to finally be able to configure this board with actual jumpers vs soldering wires.

Sent from my iPad

> On Jul 30, 2022, at 5:57 PM, norberto.collado koyado.com <norberto...@koyado.com> wrote:
>
> I'm still working on the build-out of the H8-Z5-4 board. I took a picture to compare against the original board as I did try to make it the same as much possible.
> To view this discussion on the web visit https://groups.google.com/d/msgid/sebhc/SN6PR01MB3855F4E24D89EA466496FE13F7989%40SN6PR01MB3855.prod.exchangelabs.com.
H8-Z5-4 board.jpg

norberto.collado koyado.com

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Jul 31, 2022, 4:29:43 PM (8 days ago) Jul 31
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I do not think the relay are solid state. Here is the one I purchased.

 

https://www.jameco.com/z/JWD-171-25-TE-Connectivity-SPST-NC-PC-Mount-Relay-5Volt-200-Ohm-500mA_2276871.html

 

I just calibrated the board. I order two different PLL Clock Synthesizer and one work nicely. The other couldn’t reach the 2.4KHz signal. I think it might need some resistor tweaking.

 

This one worked fine: (As I’m using 1% resistors and 1% cap for the VCO, the output frequency is very stable.)

 

https://www.jameco.com/z/CD4046B-Major-Brands-IC-CD4046-MICROPOWER-PHASE-LOCK-LOOP_13012.html

 

This one did not reach the desired frequency. It will required resistors tunning.

 

https://www.jameco.com/z/74HC4046-Major-Brands-IC-74HC4046-High-Speed-CMOS-Logic-Phase-Locked-Loop-with-VCO_45938.html

 

 

The cassette read & write circuit are working fine per scope. Next steps to add the 82C51 and test with the real cassette system. The check the H8T circuit and last the 82C51 workaround circuit.

 

Latest picture attached.

 

Thanks,

Norbert

H8-Z5-4-Calibrated.jpg

norberto.collado koyado.com

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Aug 1, 2022, 1:46:13 AM (7 days ago) Aug 1
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Glenn,

 

Test completed:

 

  1. Tested both consoles and they worked fine. Spend time testing the H8T for downloading into the board to test both consoles properly.
  2. Tested 8251 with the motor-on workaround and that fixed the issue. We can now use any 82C51 without any issues to control the cassette player/recorder.
  3. Tested H8T at 1200bps and 9600 bps without any issues.
  4. Calibration completed.

 

Test Pending:

  1. Upload/download with the cassette player
  2. Upload original H8 tapes.

 

The only issue with the layout was the Audio Dual jack, that I forgot to tell them to do square holes and not round holes. I updated the library to only use square holes. Anyhow, adding the Audio jack is optional.

 

Everything else so far checks out. Latest picture downloading files thru H8T interface. All LED’s on… 😊

 

Thanks,

Norberto

H8-Z5-4-H8T-Testing

Glenn Roberts

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Aug 1, 2022, 6:33:56 AM (7 days ago) Aug 1
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Congratulations. In my mind this largely completes the re-engineering of the key original boards. We now can make:

Backplane
Front panel
Zero org
Ram (NVRAM)
Z80 cpu (with 10Mhz+ speed; clock/calendar)
H37 interface
H17 interface
Z67 interface
Z67 itself (IDE+)
H8-4
H8-5
Ha8-2 (music synth)
Ha8-3 (sound/graphics)
PPIO (8255)
Extender board

Missing (but I think probably not needed) are
8080 cpu board
H8-2 (parallel i/o for h10)
H47 interface
H8 wire wrap board

I suppose it could be nice to build a version of the H8-7 proto board. I’ve got an original blank PCB for that if there was enough interest in cloning it…

I believe we have only the original Les Bird design for the H8-4 4-port serial board, though that’s fine, we just don’t have it in Todd’s production line. But for many the dual UART daughterboard for the Z80 CPU board may be enough (I know I only used three ports years ago: console, printer and modem, and modem is presumably only needed now for retro demonstrations)

The main piece missing to build a complete H8 is the case (and I know we’ve captured the CAD and are working on finding practical ways to generate chassis components - soon I will publish my results in creating wooden side panels, plus I’ve also created a front panel acrylic lens). 

Amazing amount of work. Thanks!

Sent from my iPad

On Aug 1, 2022, at 1:46 AM, norberto.collado koyado.com <norberto...@koyado.com> wrote:


H8-Z5-4-H8T-Testing
image001.jpg

norberto.collado koyado.com

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Aug 1, 2022, 10:43:37 AM (7 days ago) Aug 1
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From this list:

  • 8080 cpu board
  • H8-2 (parallel i/o for h10)
  • H47 interface
  • H8 wire wrap board

 

The only two boards that I have on my list are;

 

  • 8080A CPU board with 28C256 EEPROM. Not sure to add UART or not as there will be a lot of space available.
    • I will need a list on what items to add to such board.
  • H8 wire wrap board – Did some scoping with Terry S. on what the optimal wire-wrap board should be. He came with some nice ideas that I like a lot.

 

I think I have the H8-2 (parallel i/o for h10) board, but will need to check.

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Peter Higgins

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Aug 1, 2022, 3:06:40 PM (7 days ago) Aug 1
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Though I am interested, I suppose there wouldn't be enough general interest in an H47 interface to connect an 8" drive (or a Gotek emulating an 8" drive) to the H8. Complicating things is the issue that Heathkit's H47 external drive enclosure appears to have used 8" drives with a proprietary electronics board and a non-standard interface. Any idea whether it would be possible to design an H47 interface board for the H8 that would allow use of 8" drives with a standard Shugart interface?

norberto.collado koyado.com

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Aug 1, 2022, 3:42:28 PM (7 days ago) Aug 1
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For the H47, what I'm missing is the signals protocol to talk to the drive controller. I have the schematics, but no specs on how to drive the bus protocol. I need something similar to SASI specs published by Heath for the H47 interface.



From: se...@googlegroups.com <se...@googlegroups.com> on behalf of Peter Higgins <higgin...@gmail.com>
Sent: Monday, August 1, 2022 12:06 PM
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Subject: Re: [sebhc] New boards in development!
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Peter Higgins

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Aug 1, 2022, 4:14:20 PM (7 days ago) Aug 1
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Not having access to the specs for the bus protocol is a significant problem. Heathkit documented everything about the H8 so well... this seems to be the exception.

glenn.f...@gmail.com

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Aug 1, 2022, 4:33:31 PM (7 days ago) Aug 1
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I have the manual (595-2467-01), schematic and, most importantly, illustration book for the H47, though I have no actual device (nor have I ever even seen one 😊 ).

 

The illustration book has several pictorials that appear to lay out the command bytes. There’s also a “programmer’s guide” section in the manual that describes the I/O transaction sequences and more.

 

Norberto: would you like me to send this to you?

 

I could also probably scan the appropriate pages if that’s easier.  Scanning everything might be some work but I could put it in the queue…

 

 

  • Glenn

 

 

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

image001.png

Douglas Miller

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Aug 1, 2022, 5:19:29 PM (7 days ago) Aug 1
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As I recall, the "external" H47 cabinet contained a fairly-sophisticated controller - along the lines of the SASI controllers. I believe it was from a source that did not last very long, since 8" floppy use was fading at the time and the use of non-standard 8" drives was limiting/annoying. And, it was an expensive device. Heath's choice of the H47 as their 8" floppy solution was the motivation for Magnolia Microsystems to create their soft-sector 8"/5" floppy controller - a much cheaper solution.

What's the goal in resurrecting the H47? Was there some software that required an H47? Do we have a cache of 8" floppies? We could probably reverse-engineer something close to the original protocol by examining the various ROMs, drivers, and bootstraps, but without actual 8" drives and floppies I'm wondering what the appeal is?

norberto.collado koyado.com

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Aug 1, 2022, 5:36:20 PM (7 days ago) Aug 1
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Glenn,

I agree with Douglas assessment. As I like storage devices, I will be interested in getting a copy of the “programmer’s guide”. This should help me understand how to write and read a sector to an H47 device.

Duplicating the board HW is easy as there was an H89 version which is much simpler and elegant. Attaching a device to the H47 board will be something like the Z67-IDE+, but at a reduced capacity as the 8" floppies had a 1.2MB capacity x2.  So, it is not a viable option.

 I wonder in this group has a working H47 with the original drives?

We get more with Rick solution for HDOS and eventually CP/M: http://koyado.com/heathkit/New-H8-Website/download/h8-dual-f-storage-side1-view.png







From: se...@googlegroups.com <se...@googlegroups.com> on behalf of Douglas Miller <durga...@gmail.com>
Sent: Monday, August 1, 2022 2:19 PM
To: se...@googlegroups.com <se...@googlegroups.com>

Glenn Roberts

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Aug 1, 2022, 9:40:37 PM (7 days ago) Aug 1
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I’ll scan the key pages soon and share them.  ….

Sent from my iPad

On Aug 1, 2022, at 5:36 PM, norberto.collado koyado.com <norberto...@koyado.com> wrote:


Glenn,

I agree with Douglas assessment. As I like storage devices, I will be interested in getting a copy of the “programmer’s guide”. This should help me understand how to write and read a sector to an H47 device.

Duplicating the board HW is easy as there was an H89 version which is much simpler and elegant. Attaching a device to the H47 board will be something like the Z67-IDE+, but at a reduced capacity as the 8" floppies had a 1.2MB capacity x2.  So, it is not a viable option.

 I wonder in this group has a working H47 with the original drives?

We get more with Rick solution for HDOS and eventually CP/M: http://koyado.com/heathkit/New-H8-Website/download/h8-dual-f-storage-side1-view.png







From: se...@googlegroups.com <se...@googlegroups.com> on behalf of Douglas Miller <durga...@gmail.com>
Sent: Monday, August 1, 2022 2:19 PM
To: se...@googlegroups.com <se...@googlegroups.com>
Subject: Re: [sebhc] New boards in development!
 

As I recall, the "external" H47 cabinet contained a fairly-sophisticated controller - along the lines of the SASI controllers. I believe it was from a source that did not last very long, since 8" floppy use was fading at the time and the use of non-standard 8" drives was limiting/annoying. And, it was an expensive device. Heath's choice of the H47 as their 8" floppy solution was the motivation for Magnolia Microsystems to create their soft-sector 8"/5" floppy controller - a much cheaper solution.

What's the goal in resurrecting the H47? Was there some software that required an H47? Do we have a cache of 8" floppies? We could probably reverse-engineer something close to the original protocol by examining the various ROMs, drivers, and bootstraps, but without actual 8" drives and floppies I'm wondering what the appeal is?


On 8/1/22 15:33, glenn.f...@gmail.com wrote:

I have the manual (595-2467-01), schematic and, most importantly, illustration book for the H47, though I have no actual device (nor have I ever even seen one 😊 ).

 

The illustration book has several pictorials that appear to lay out the command bytes. There’s also a “programmer’s guide” section in the manual that describes the I/O transaction sequences and more.

 

Norberto: would you like me to send this to you?

 

I could also probably scan the appropriate pages if that’s easier.  Scanning everything might be some work but I could put it in the queue…

 

 

  • Glenn

 

 

From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of norberto.collado koyado.com
Sent: Monday, August 01, 2022 3:42 PM
To: SEBHC <se...@googlegroups.com>
Subject: Re: [sebhc] New boards in development!

 

For the H47, what I'm missing is the signals protocol to talk to the drive controller. I have the schematics, but no specs on how to drive the bus protocol. I need something similar to SASI specs published by Heath for the H47 interface.

 

image001.png

Peter Higgins

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Aug 1, 2022, 11:09:06 PM (6 days ago) Aug 1
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The reason I am interested in H8 8" drive support is because I have several different computer systems running CP/M all of which have 8"  drives. Transferring software and data between them is easy since they all have in common the 8" SSSD CP/M disk format.
While I have the H47 controller board, I don't have the external drive system. My impression is that few H47 drive systems were sold, and very few have survived to this day.

Douglas Miller

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Aug 1, 2022, 11:28:46 PM (6 days ago) Aug 1
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Just to be precise, the H47 board that plugs into the H8 is an *interface* board, not a controller. It is a fairly simple circuit, similar in complexity to that used for the H67 interface (i.e. a custom parallel port). The external box with the 8" drives contains the controller, which has a CPU and FDC chip and associated hardware and firmware. The external H47 cabinet is not simply a container for 8" drives.

In the absence of a working H47 controller, one would need working 8" floppy drives and a new controller (with floppy interface) programmed to emulate the H47 protocol. I think the actual designer/manufacturer of the "H47" controller was Remex, but that probably doesn't help.

If you're just looking for data transfer, there may be better ways. There are also other ways to get 8" floppy drives onto an H8 - one of which would be to replicate the Magnolia Microsystems H89 board onto an H8 format.

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Peter Higgins

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Aug 2, 2022, 12:49:18 AM (6 days ago) Aug 2
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Yes, I do realize the H47 board for the H8 was simply an interface, and that the H47 external enclosure has all the circuitry required to control the drive and read/write data to and from the drive. Replicating all that circuitry (ie the floppy controller and a microprocessor) on an H8 board so that standard Shugart-interface 8" drives can be connected would be a significant project. As I mentioned before, it is unlikely there are enough of us interested in using 8" drives on the H8 to make it worth the design effort involved.

I have used other methods (like Xmodem) to transfer data between two computers running CP/M and I agree, there is no really good reason to connect an 8" drive to an H8 other than to demonstrate it was (and can still be) done.

norberto.collado koyado.com

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Aug 2, 2022, 1:27:21 AM (6 days ago) Aug 2
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An H8-H37 can be modified to talk to 8” floppies. It needs the breakout board to convert from 34 pin to 50 pin. I might have some in my toolbox.

 

Norberto

 

From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of Peter Higgins
Sent: Monday, August 1, 2022 9:49 PM
To: SEBHC <se...@googlegroups.com>
Subject: Re: [sebhc] New boards in development!

 

Yes, I do realize the H47 board for the H8 was simply an interface, and that the H47 external enclosure has all the circuitry required to control the drive and read/write data to and from the drive. Replicating all that circuitry (ie the floppy controller and a microprocessor) on an H8 board so that standard Shugart-interface 8" drives can be connected would be a significant project. As I mentioned before, it is unlikely there are enough of us interested in using 8" drives on the H8 to make it worth the design effort involved.

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norberto.collado koyado.com

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Aug 2, 2022, 2:01:50 AM (6 days ago) Aug 2
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Thanks  Glenn!

 

The new H8-Z5-4 loaded the original H8 tapes. This is a great achievement. Also, it read tapes created with your H8-5 boards.

 

Next step is to create my own tapes and be able to read them…

 

Norberto

Peter Higgins

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Aug 2, 2022, 9:55:14 AM (6 days ago) Aug 2
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I also have a 34 pin to 50 pin floppy adapter - very useful for imaging 8" floppy disks using a PC.

Such an adapter would allow the H8-37 to talk to an 8" drive. For H8 CP/M to read and write to that drive using an 8" floppy drive format would require rewriting the disk format and drive controller code in the CP/M BIOS... which I suppose is still easier than designing an H8 floppy drive controller board for 8" drives.

Douglas Miller

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Aug 2, 2022, 11:17:34 AM (6 days ago) Aug 2
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I think a modified H37 could be used to do single-density 8" diskettes. DD 8" would be more of a challenge, especially at the original 2MHz CPU speed.

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Peter Higgins

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Aug 2, 2022, 11:46:49 AM (6 days ago) Aug 2
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Excellent point. Also, I expect the H37 controller will not be able to support the data rate of 8" DD which is twice that of 5.25" DD.

Glenn Roberts

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Aug 2, 2022, 1:33:06 PM (6 days ago) Aug 2
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Norberto has designed support for 8” drives into his H8-Z37 board design, so if you have one of his new controllers you should be able to do this. I’m sure he can weigh in on any questions.

 

From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of Peter Higgins
Sent: Tuesday, August 02, 2022 11:47 AM
To: SEBHC <se...@googlegroups.com>
Subject: Re: [sebhc] New boards in development!

 

Excellent point. Also, I expect the H37 controller will not be able to support the data rate of 8" DD which is twice that of 5.25" DD.

On Tuesday, August 2, 2022 at 8:17:34 AM UTC-7 Douglas Miller wrote:

I think a modified H37 could be used to do single-density 8" diskettes. DD 8" would be more of a challenge, especially at the original 2MHz CPU speed.

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norberto.collado koyado.com

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Aug 2, 2022, 5:34:14 PM (6 days ago) Aug 2
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I tested HDD floppy media on a 3.5" floppy drive running the clock at the Floppy Controller @2MHz attached to the H37 controller.  If I recall properly, I had to run the Z80 at 8MHz to get best performance at such HDD density. 

You could create a newer H47 controller but requires some heavy lifting by re-creating the H47 interface and at the other end have a Z80 with FW with the H37 circuit attached to an 8" floppy drive.

Something like this:

H47 <-> Z80 @ 10MHz (EEPROM/RAM) <-> H37 floppy controller <-> 8" floppy drive  (will need a nice logic analyzer to debug this)

We have these components and the only thing to design will be the "Z80 @ 10MHz (EEPROM/RAM)" circuitry to talk to the H47 and the H37 controller. It will be cool to have the H47 floppy case to see what they used inside such box to manage the floppy drive.

Norberto


Sent: Tuesday, August 2, 2022 8:46 AM

To: SEBHC <se...@googlegroups.com>
Subject: Re: [sebhc] New boards in development!
Excellent point. Also, I expect the H37 controller will not be able to support the data rate of 8" DD which is twice that of 5.25" DD.

On Tuesday, August 2, 2022 at 8:17:34 AM UTC-7 Douglas Miller wrote:

I think a modified H37 could be used to do single-density 8" diskettes. DD 8" would be more of a challenge, especially at the original 2MHz CPU speed.

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Peter Higgins

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Aug 2, 2022, 6:33:50 PM (6 days ago) Aug 2
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I should have looked this up earlier - there is a lot of excellent information on the topic of the H8 and 8" floppy drives from this discussion in 2018:

Mark Garlanger

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Aug 2, 2022, 6:50:56 PM (6 days ago) Aug 2
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The controller on the H47 was actually part of one of the drives.  Remex had a master drive and a slave drive, the H47 used one of each. I do have the docs somewhere. I also have an H47 case/drives but won't be able to get it out anytime soon, due to fractures in my back from a rollover accident. 

Mark

John Evans

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Aug 2, 2022, 7:03:12 PM (6 days ago) Aug 2
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Oh man, here's best wishes that you heal and recover quickly.

John


On Tue, Aug 2, 2022, 16:51 Mark Garlanger <garl...@gmail.com> wrote:
....but won't be able to get it out anytime soon, due to fractures in my back from a rollover accident. 

Mark

Mark Garlanger

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Aug 2, 2022, 11:27:50 PM (5 days ago) Aug 2
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Thanks John, it was kinda crazy going from driving down the road at about 50 mph, to immediately rolling three times and having the car stop with the driver side on the ground. Luckily, I always wear my seatbelt, or it could have been much worse. 

Mark

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norberto.collado koyado.com

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Aug 3, 2022, 12:37:43 AM (5 days ago) Aug 3
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WOW! Please take care of yourself!

 

Norberto

 

From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of Mark Garlanger
Sent: Tuesday, August 2, 2022 8:28 PM
To: se...@googlegroups.com
Subject: Re: [sebhc] New boards in development!

 

Thanks John, it was kinda crazy going from driving down the road at about 50 mph, to immediately rolling three times and having the car stop with the driver side on the ground. Luckily, I always wear my seatbelt, or it could have been much worse. 

Joseph Travis

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Aug 3, 2022, 8:54:45 AM (5 days ago) Aug 3
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Mark,

I wish you all the best for a speedy recovery.  I can empathize with you as it's been 10 years since I laid down my Harley at 75+ mph and I'm still recovering from that experience.

Regards,
Joe Travis n6ypc


norberto.collado koyado.com

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Aug 3, 2022, 6:11:25 PM (5 days ago) Aug 3
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Glenn,



Missing (but I think probably not needed) are 8080 CPU board...

To create a new version of the 8080A CPU board will be hard as the "8238 system controller and bus driver" is not easy to get. I see such IC in ebay. The replacement for the 8080A was the 8085A. 

Norberto

From: se...@googlegroups.com <se...@googlegroups.com> on behalf of Glenn Roberts <glenn.f...@gmail.com>
Sent: Monday, August 1, 2022 3:33 AM
To: se...@googlegroups.com <se...@googlegroups.com>

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glenn.f...@gmail.com

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Aug 3, 2022, 6:25:25 PM (5 days ago) Aug 3
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IMO not necessary given that we have Z80 boards.  For historical correctness we can use original 8080 boards to demonstrate early systems…

image001.jpg

norberto.collado koyado.com

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Aug 3, 2022, 6:58:00 PM (5 days ago) Aug 3
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We can reproduce it exactly as long you can get such parts at eBay. The other parts are easy to get. The voltage regulators will need to be updated.

I was just reading the specs of the "8238 IC" and it is just a buffer and a latch which can be easily integrated with the newer components. 

I see two paths for such board.

Norberto



From: se...@googlegroups.com <se...@googlegroups.com> on behalf of glenn.f...@gmail.com <glenn.f...@gmail.com>
Sent: Wednesday, August 3, 2022 3:25 PM

Peter Higgins

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Aug 3, 2022, 8:43:22 PM (5 days ago) Aug 3
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Re reproducing the 8080 CPU board...
As you pointed out, the 8238 is easy to replicate with individual bus drivers, a latch, and a few gates to generate the bus control signals.
The part that is not at all easy to replicate is the 8224 clock generator and driver. Like the 8238, it is also not easily found.

A supplier for long obsolete parts like this (besides eBay) is UTSource - their web site indicates they currently have stock on both these parts:
Another source for these parts (based in the US) is Unicorn Electronics:

Douglas Miller

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Aug 3, 2022, 8:58:59 PM (5 days ago) Aug 3
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Couldn't a CPLD replace both?

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Peter Higgins

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Aug 3, 2022, 9:42:13 PM (5 days ago) Aug 3
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A CPLD could easily replace the 8238, and some of the functions of the 8224.
The 8080 requires a non-overlapping two-phase clock, with specific requirements for the pulse width of each clock signal. The 8080 clock inputs require a logic low with a max of 0.8V and logic high with a minimum 9V.  Meeting these requirements with a CPLD would require additional components, so the 8224 is still the most elegant solution.

Joseph Travis

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Aug 3, 2022, 10:52:12 PM (4 days ago) Aug 3
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How much demand is there for a new 8080 CPU Board?  Why not skip the 8080 / 8085 and use a V20 CPU with 1MB RAM instead? In an H8 it could start up in 8080 mode and switch to 80186 mode for CP/M+ or CP/M-86 (or MS-DOS).  They are available in 5, 8 or 10 MHz versions.   The V20 uses an 8 bit data bus which allows it to work with existing hardware.

It uses 3 byte instructions to switch between 8 bit (8080) and 16 bit (80186) modes.  In 8080 mode, it can also make calls to 80186 code which would allow access to much more memory for use with CP/M+.  'Just a thought...

Regards,
Joe Travis n6ypc


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rand...@hotmail.com

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Aug 3, 2022, 10:57:30 PM (4 days ago) Aug 3
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The 8080 is another obsolete part.

The 8224 could be replaced with a CPLD and a transistor. 

The bigger question is why when there are third-party replacements. 

Of course with a $20 FPGA board (CycloneII) and some level converters could replace the whole board and more.

The point of a "new" 8080 board is the old tech.


Randy

norberto.collado koyado.com

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Aug 3, 2022, 11:43:59 PM (4 days ago) Aug 3
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Thank you for the link. Unicorn is less expensive. So, we can reproduce original board with such parts + the new improvements.

 

I’m just brainstorming here:

  1. Do we add 64KB of RAM to the board?
  2. For sure a 28C256 EEPROM.
  3. Do we add the HA8-8 Extended Configuration?

 

Norberto

 

From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of Peter Higgins
Sent: Wednesday, August 3, 2022 5:43 PM
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Subject: Re: [sebhc] New boards in development!

 

Re reproducing the 8080 CPU board...

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Richard Davis Jr.

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Aug 4, 2022, 6:25:30 AM (4 days ago) Aug 4
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Norbeto,

If you do make this board, I would say yes to RAM and config 0.

Rick


rand...@hotmail.com

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Aug 4, 2022, 9:36:40 AM (4 days ago) Aug 4
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Why 64k of RAM, use a 1504 CPLD to make a MMU and use a 512k RAM chip.


Randy

norberto.collado koyado.com

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Aug 4, 2022, 11:17:53 AM (4 days ago) Aug 4
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Do you have a design with the 1504 cPLD that I could leverage? We have the 512KB board already. A 64KB RAM is simpler design.

From: se...@googlegroups.com <se...@googlegroups.com> on behalf of rand...@hotmail.com <rand...@hotmail.com>
Sent: Thursday, August 4, 2022 6:36:40 AM

rand...@hotmail.com

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Aug 4, 2022, 11:45:41 AM (4 days ago) Aug 4
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I don't really recommend any RAM on board but if you do here is probably the best MMU (says Z80 but really any 8 bit processor):


The best part is since it emulated the Z180 MMU there is plenty of references to look at.


Randy

Douglas Miller

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Aug 4, 2022, 11:47:53 AM (4 days ago) Aug 4
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Is there a demand for more than 64K on an 8080? Note that MMS CP/M 3 is written for a Z80 (H89) and would require a major rewrite to work on 8080. Even the current MP/M-II I have is written for the Z80.

But, if you're going to add an MMU to the 8080 CPU board, I'd recommend trying to make it software compatible with the H8-512K-MMU. Otherwise, it's just more obscure hardware that people need to be convinced to port software to.

My two cents.

norberto.collado koyado.com

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Aug 4, 2022, 11:56:25 AM (4 days ago) Aug 4
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64KB it is. We have in the works a Z180 CPU design with 1MB of RAM. I do not see the need for more than 64KB for the 8080A CPU board.

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Sent: Thursday, August 4, 2022 8:47:49 AM
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norberto.collado koyado.com

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Aug 4, 2022, 1:48:16 PM (4 days ago) Aug 4
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Any reason why I cannot run PAM-37 on the 8080A CPU board?

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Sent: Thursday, August 4, 2022 8:56:19 AM

Douglas Miller

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Aug 4, 2022, 1:51:08 PM (4 days ago) Aug 4
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Does PAM-37 have Z80 code? I know it preserves Z80 registers, but not sure how well guarded that code is (does it auto-detect an 8080?)

Glenn Roberts

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Aug 4, 2022, 1:53:45 PM (4 days ago) Aug 4