New H89 Baseboard! Please review and provide feedback.

[norberto.collado koyado.com]

Attached are the schematics for a new H89 baseboard. I used the DG Super89 design as a baseline and added the new features.

 

Please review and provide feedback.

 

New H89 Baseboard Features:

 

1. Fully Heath Compatible
2. 256KB Read/Write EEPROM Monitor
3. 512KB of RAM with battery backup to boot HDOS 2, HDOS 3, CPM, MMS CPM3, and MPM. Supports memory Floppy drive.
4. CPU speed software selectable: 2MHz, 4MHz, 8MHz, and 16MHz with indicators.
5. Wait states when running at 8MHz and 16MHz
6. I2C Real Time Clock
7. I2C OLED Display header for power-on and system messages
8. UART’s Clocks software selectable: 1.8432MHz and 3.6864MHz to run at high speeds
9. USB flash drive support by using VDIP1 controller
10. H37 jumper selectable support
11. 2x USART 16C550 on baseboard
12. SPI Wiznet controller to provide HDOS and CPM network support
13. SPI NVRAM for network and system configuration setup
14. 6 slots for I/O configuration
15. Updated right slots to handle 270Q->277Q range to support H17, H37, and H67 at same time.
16. USB-TTL header for both UARTS

 

 

Thanks,

Norberto

[rw...@robhome.com]

Wow! That looks great! Do you expect this to be a drop in replacement for the standard H-89 mainboard? I have an H-89 with a failed mainboard, this would be great!

Thanks for all you do!

Rob Waggoner
615-260-6903

From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of norberto.collado koyado.com
Sent: Wednesday, March 5, 2025 7:41 PM
To: sebhc Google Group <se...@googlegroups.com>
Subject: [sebhc] New H89 Baseboard! Please review and provide feedback.

Attached are the schematics for a new H89 baseboard. I used the DG Super89 design as a baseline and added the new features.

Please review and provide feedback.

New H89 Baseboard Features:

1. Fully Heath Compatible
2. 256KB Read/Write EEPROM Monitor
3. 512KB of RAM with battery backup to boot HDOS 2, HDOS 3, CPM, MMS CPM3, and MPM. Supports memory Floppy drive.
4. CPU speed software selectable: 2MHz, 4MHz, 8MHz, and 16MHz with indicators.
5. Wait states when running at 8MHz and 16MHz
6. I2C Real Time Clock
7. I2C OLED Display header for power-on and system messages
8. UART’s Clocks software selectable: 1.8432MHz and 3.6864MHz to run at high speeds
9. USB flash drive support by using VDIP1 controller
10. H37 jumper selectable support
11. 2x USART 16C550 on baseboard
12. SPI Wiznet controller to provide HDOS and CPM network support
13. SPI NVRAM for network and system configuration setup
14. 6 slots for I/O configuration
15. Updated right slots to handle 270Q->277Q range to support H17, H37, and H67 at same time.
16. USB-TTL header for both UARTS


Thanks,
Norberto
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[norberto.collado koyado.com]

Yes, it should be a replacement with the ability to boot MMS CPM3 + MPM.

 

From: se...@googlegroups.com <se...@googlegroups.com> on behalf of rw...@robhome.com <rw...@robhome.com>
Date: Wednesday, March 5, 2025 at 7:47 PM
To: sebhc Google Group <se...@googlegroups.com>
Subject: [sebhc] RE: New H89 Baseboard! Please review and provide feedback.

Wow! That looks great! Do you expect this to be a drop in replacement for the standard H-89 mainboard? I have an H-89 with a failed mainboard, this would be great!

 

Thanks for all you do!

 

Rob Waggoner

615-260-6903

 

From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of norberto.collado koyado.com
Sent: Wednesday, March 5, 2025 7:41 PM
To: sebhc Google Group <se...@googlegroups.com>
Subject: [sebhc] New H89 Baseboard! Please review and provide feedback.

 

Attached are the schematics for a new H89 baseboard. I used the DG Super89 design as a baseline and added the new features.

 

Please review and provide feedback.

 

New H89 Baseboard Features:

 

1. Fully Heath Compatible
2. 256KB Read/Write EEPROM Monitor

1. 512KB of RAM with battery backup to boot HDOS 2, HDOS 3, CPM, MMS CPM3, and MPM. Supports memory Floppy drive.

1. CPU speed software selectable: 2MHz, 4MHz, 8MHz, and 16MHz with indicators.

1. Wait states when running at 8MHz and 16MHz

1. I2C Real Time Clock

1. I2C OLED Display header for power-on and system messages

1. UART’s Clocks software selectable: 1.8432MHz and 3.6864MHz to run at high speeds

1. USB flash drive support by using VDIP1 controller

1. H37 jumper selectable support

1. 2x USART 16C550 on baseboard

1. SPI Wiznet controller to provide HDOS and CPM network support

1. SPI NVRAM for network and system configuration setup

1. 6 slots for I/O configuration

1. Updated right slots to handle 270Q->277Q range to support H17, H37, and H67 at same time.

1. USB-TTL header for both UARTS

 

 

Thanks,

Norberto

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[Joseph Travis]

It looks good, Norberto!  I have a few suggestions when you layout the board:

1.  Use Polulu regulators so the heatsink / mounting bracket isn't required. (We'll come up with another way to secure the board.)

2.  Make the board dimensions the same as the old CPU board with the bracket.  This gives you more real estate for layout purposes.

3.  Layout the 10/11 pin connectors such that they are staggered (the 10 pins are adjacent to but in between the 11 pins).

4.  Place the 4 pin power connection near the upper right corner of the board so the cable no longer has to cross over the I/O boards.

BR,

Joe

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[Darrell Pelan]

Awesome! Thanks for all your hard work.

   Darrell

[norberto.collado koyado.com]

1. Use Polulu regulators so the heatsink / mounting bracket isn't required. (We'll come up with another way to secure the board.) – OK, will add them. Due to shipping tariffs, duplicating same mounting bracket will be expensive.

2.  Make the board dimensions the same as the old CPU board with the bracket.  This gives you more real estate for layout purposes. – Terry S. will help me with the mechanical section to layout the components properly.

3.  Layout the 10/11 pin connectors such that they are staggered (the 10 pins are adjacent to but in between the 11 pins). – Terry S. will help me out with that.

4.  Place the 4 pin power connection near the upper right corner of the board so the cable no longer has to cross over the I/O boards. - Will do the same as the DG Super89 board per attached picture..

 

 

Thanks for the feedback.

 

Norberto

 

To view this discussion visit https://groups.google.com/d/msgid/sebhc/CAGQDgBCUHnvQtb4CFDGhVFoPFVMWP21v_goE1058RNKTZSwyNA%40mail.gmail.com.

[norberto.collado koyado.com]

Is there a technical reason on why the addresses are latched on the H89 system? Can I eliminate them and use regular buffers instead of the flip-flops?

 

 

Thanks,

Norberto

 

 

[Joseph Travis]

I believe the latches are necessary to guarantee proper setup & hold times.

Joe

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