H8 PC-12 8255 I/O card

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Norberto Collado

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Oct 17, 2020, 5:29:59 AM10/17/20
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Glenn,

 

After seeing Terry’s Smedley H8 system (picture attached), it highlighted the need to duplicate the PC-12 card for the H8 as I do not have such board in my collection. He provided the schematics and documentation for such board.

 

I will add this board to my list of new boards.

 

As you have a similar one, let me know if any changes needed. I do not see the need to use the RTC clock attached to a 8255 IC.

 

For the parallel printer, I can use same circuit and header as the one used on the H89 board.

 

Thanks,

 

Norberto

H8_Overview.jpg
PC-12_Board_Layout.pdf
H89-RTC-SPEED-PARALLEL.jpg

Joseph Travis

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Oct 17, 2020, 7:55:42 AM10/17/20
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Norberto,

Why not use a 26 pin (2x13) header which would permit using a ribbon cable to connect with a Centronics connector?

Joe

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Glenn Roberts

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Oct 17, 2020, 10:11:49 AM10/17/20
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The board I have is an “Environmental Control Systems PC-12A, Rev. C”

 

Here’s an ad they had in Sextant:

 

 

Unfortunately, I have only the board itself, not the “extensive documentation and support software” ☹  However it was easy to set this up as a CP/M parallel printer by adapting a BIOS (I think I got this from Ken?) for the “2/3rds H89 serial/parallel board” from Secured Computer Systems.  Don’t think I ever built an HDOS driver (?) but again probably pretty straightforward.

 

Here are pictures of the board

 

https://photos.app.goo.gl/CUD1LqTbjrKcUgtJA

 

It has five 8255s, but one of those is for the clock interface.  I agree any new board we make would not need the real time clock part.

 

I am impressed with the versatility of the board and the three different ways they bring out the pin-outs for the parallel interfaces (DIP sockets, direct solder tabs, and .1” headers).  I fabricated a ribbon cable that connects two 14-pin DIP connectors to a “PC style” parallel cable (DB25 to Centronics).  I agree with Joe that we should have multiple ways to bring the parallel ports out depending on what people want to use it for.  Here are my notes on how I set up the Centronics interface.

 

 

 

Let me know if you need me to do anything more on this of if the picture is enough for you to understand the board.

 

Thanks!

 

  • Glenn

 

 

image001.png
image002.png

Glenn Roberts

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Oct 17, 2020, 10:19:20 AM10/17/20
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Sorry. Saw your original email on my iPad and hadn’t opened the attachments.  Looks like the schematic is for the same board I have (though the one pictured has a different way of bringing out the pins).

 

Also Terry’s H8 setup looks quite cool.  Amazingly clean – like new!  Terry: are you on the list?  can you describe your system and what the various breakout boards are that you’re interfacing to?  Very nice!  also what CPU board is that?

 

Thanks!

 

  • Glenn

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Norberto Collado

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Oct 17, 2020, 5:28:55 PM10/17/20
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Why not use a 26 pin (2x13) header which would permit using a ribbon cable to connect with a Centronics connector?

 

 

That is the plan on one of them.

Norberto Collado

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Oct 17, 2020, 5:30:32 PM10/17/20
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Thanks Glenn and I have enough information to build/improve such baseboard.

 

Norberto

 


Reply-To: "se...@googlegroups.com" <se...@googlegroups.com>
Date: Saturday, October 17, 2020 at 7:11 AM
To: "se...@googlegroups.com" <se...@googlegroups.com>

Norberto Collado

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Oct 17, 2020, 8:15:36 PM10/17/20
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Glenn,

 

Which I/O Port are you using for the 8255A attached to your parallel printer?

 

Norberto

Glenn Roberts

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Oct 17, 2020, 10:01:28 PM10/17/20
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I don’t have that system configured and running now but from looking at my listings I believe it’s 320Q (0xD0).  I believe it was the left-most port on the board (port 1).

image001.png
image002.png

Norberto Collado

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Oct 17, 2020, 10:18:41 PM10/17/20
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That is the same port I'm using on the H89 Parallel Port. So we are good.

Thanks,
Norberto
H89-Printer_Parallel_Port.PNG

Mark Garlanger

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Oct 17, 2020, 11:11:46 PM10/17/20
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I have an H89 with the Environmental Control Systems PC89, and I think I have manuals and some disks for it.

Mark

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Glenn Roberts

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Oct 18, 2020, 3:02:06 AM10/18/20
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Great!

Sent from my iPad

On Oct 17, 2020, at 11:11 PM, Mark Garlanger <garl...@gmail.com> wrote:


<image001.png>
 
Unfortunately, I have only the board itself, not the “extensive documentation and support software” ☹  However it was easy to set this up as a CP/M parallel printer by adapting a BIOS (I think I got this from Ken?) for the “2/3rds H89 serial/parallel board” from Secured Computer Systems.  Don’t think I ever built an HDOS driver (?) but again probably pretty straightforward.
 
Here are pictures of the board
 
https://photos.app.goo.gl/CUD1LqTbjrKcUgtJA
 
It has five 8255s, but one of those is for the clock interface.  I agree any new board we make would not need the real time clock part.
 
I am impressed with the versatility of the board and the three different ways they bring out the pin-outs for the parallel interfaces (DIP sockets, direct solder tabs, and .1” headers).  I fabricated a ribbon cable that connects two 14-pin DIP connectors to a “PC style” parallel cable (DB25 to Centronics).  I agree with Joe that we should have multiple ways to bring the parallel ports out depending on what people want to use it for.  Here are my notes on how I set up the Centronics interface.
 
 
<image002.png>

Terry Smedley

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Oct 18, 2020, 9:26:30 AM10/18/20
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Glenn:

About my H8 system:  
The CPU is the Trionyx 2/4MHz Z80 board (also have the Trionyx backplane and 64K memory card).

The PC-12 8255 card interfaces to:
"bit banged" I2C, for H8/H17-37 temperature, voltage, and current measurements
tachometers and speed control for fans in the H8 and H17/37 cabinets
20x4 line LCD for real-time temp, volts, amp displays
Digitalker speech board
home-brew burner for 2532 and 2764 EPROMs

That string of prototype boards affixed to the left-hand panel is, from front to back:
1) 4-channel ADC, using an Adafruit ADC1015 breakout.  Monitors voltage on the supplies for +3.3 and +5v on the I2C buses, voltage and current on the H8 +8v supply.  +8v current is measured by a Pololu Hall-effect current sensor breakout mounted near the capacitor.  The ADC board is mounted on top of a 80mm fan.
2) 3.3v supply for those I2C devices that aren't 5v tolerant.  Mounted on the side of the 80mm fan.
3) two-channel I2C distribution bus (one channel is 3.3v, the other is 5v)
4) 8255 -> two-channel I2C bus master
5) collector/distributor for fan tachometers and power (1x80mm, 2x40mm Noctua fans in the H8; 1x80mm Noctua in the H17/37 cabinet)

A background process (hooked into the 2ms clock interrupt vector) displays the temps/volts/amps on the 20x4 LCD, and adjusts fan speeds based on interior temperatures.

Terry

Dave McGuire

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Oct 19, 2020, 12:18:39 AM10/19/20
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Wow...WOW! That's quite an H8! VERY nice. I'd love to see pics of
that setup.

-Dave

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Mark Garlanger

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Oct 19, 2020, 12:58:23 AM10/19/20
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Norberto posted a photo of Terry's H8, in the first message in this thread.

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Dave McGuire

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Oct 19, 2020, 1:03:41 AM10/19/20
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I missed that; I will go dig it up and take a look. Thank you for
pointing it out.

-Dave
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Norberto Collado

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Oct 19, 2020, 2:08:25 AM10/19/20
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Mark,

Ken shared with me the PC89 information to developed the H89 Parallel board.

Please check the website to find out what we are missing.


Thanks,
Norberto
-------- Original Message --------
Subject: Re: [sebhc] H8 PC-12 8255 I/O card
From: Glenn Roberts <glenn.f...@gmail.com>
Date: Sun, October 18, 2020 12:02 am
To: se...@googlegroups.com

Great!

Sent from my iPad

On Oct 17, 2020, at 11:11 PM, Mark Garlanger <garl...@gmail.com> wrote:


I have an H89 with the Environmental Control Systems PC89, and I think I have manuals and some disks for it.

Mark

On Sat, Oct 17, 2020 at 9:18 PM Norberto Collado <norberto...@koyado.com> wrote:
That is the same port I'm using on the H89 Parallel Port. So we are good.

Thanks,
Norberto
-------- Original Message --------
Subject: RE: [sebhc] H8 PC-12 8255 I/O card
From: "Glenn Roberts" <glenn.f...@gmail.com>
Date: Sat, October 17, 2020 7:01 pm
To: <se...@googlegroups.com>

I don’t have that system configured and running now but from looking at my listings I believe it’s 320Q (0xD0).  I believe it was the left-most port on the board (port 1).
 
From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of Norberto Collado
Sent: Saturday, October 17, 2020 8:16 PM
To: se...@googlegroups.com
Subject: Re: [sebhc] H8 PC-12 8255 I/O card
 
Glenn,
 
Which I/O Port are you using for the 8255A attached to your parallel printer?
 
Norberto
 
From: "se...@googlegroups.com" <se...@googlegroups.com> on behalf of Norberto Collado <norberto...@koyado.com>
Reply-To: "se...@googlegroups.com" <se...@googlegroups.com>
Date: Saturday, October 17, 2020 at 2:30 PM
To: "se...@googlegroups.com" <se...@googlegroups.com>
Subject: Re: [sebhc] H8 PC-12 8255 I/O card
 
Thanks Glenn and I have enough information to build/improve such baseboard.
 
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: Saturday, October 17, 2020 at 7:11 AM
To: "se...@googlegroups.com" <se...@googlegroups.com>
Subject: RE: [sebhc] H8 PC-12 8255 I/O card
 
The board I have is an “Environmental Control Systems PC-12A, Rev. C”
 
Here’s an ad they had in Sextant:
 
<image001.png>
 
Unfortunately, I have only the board itself, not the “extensive documentation and support software” ☹  However it was easy to set this up as a CP/M parallel printer by adapting a BIOS (I think I got this from Ken?) for the “2/3rds H89 serial/parallel board” from Secured Computer Systems.  Don’t think I ever built an HDOS driver (?) but again probably pretty straightforward.
 
Here are pictures of the board
 
https://photos.app.goo.gl/CUD1LqTbjrKcUgtJA
 
It has five 8255s, but one of those is for the clock interface.  I agree any new board we make would not need the real time clock part.
 
I am impressed with the versatility of the board and the three different ways they bring out the pin-outs for the parallel interfaces (DIP sockets, direct solder tabs, and .1” headers).  I fabricated a ribbon cable that connects two 14-pin DIP connectors to a “PC style” parallel cable (DB25 to Centronics).  I agree with Joe that we should have multiple ways to bring the parallel ports out depending on what people want to use it for.  Here are my notes on how I set up the Centronics interface.
 
 
<image002.png>
 
Let me know if you need me to do anything more on this of if the picture is enough for you to understand the board.
 
Thanks!
 
  • Glenn
 
 
From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of Joseph Travis
Sent: Saturday, October 17, 2020 7:55 AM
To: se...@googlegroups.com
Subject: Re: [sebhc] H8 PC-12 8255 I/O card
 
Norberto,
 
Why not use a 26 pin (2x13) header which would permit using a ribbon cable to connect with a Centronics connector?
 
Joe
 
On Sat, Oct 17, 2020, 5:30 AM Norberto Collado <norberto...@koyado.com> wrote:
Glenn,
 
After seeing Terry’s Smedley H8 system (picture attached), it highlighted the need to duplicate the PC-12 card for the H8 as I do not have such board in my collection. He provided the schematics and documentation for such board.
 
I will add this board to my list of new boards.
 
As you have a similar one, let me know if any changes needed. I do not see the need to use the RTC clock attached to a 8255 IC.
 
For the parallel printer, I can use same circuit and header as the one used on the H89 board.
 
Thanks,
 
Norberto
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Norberto Collado

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Oct 19, 2020, 2:35:54 AM10/19/20
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Glenn,

Attached are the preliminary schematics (WIP)  for the H8-PPIO-Controller. One PPIO dedicated to the Parallel Printer on Port 320Q and another dedicated to do I2C communications. Added the I2C RTC, I2C ROM and I2C eXpander.

Thanks,
Norberto 

 
Unfortunately, I have only the board itself, not the “extensive documentation and support software” ☹  However it was easy to set this up as a CP/M parallel printer by adapting a BIOS (I think I got this from Ken?) for the “2/3rds H89 serial/parallel board” from Secured Computer Systems.  Don’t think I ever built an HDOS driver (?) but again probably pretty straightforward.
 
Here are pictures of the board
 
https://photos.app.goo.gl/CUD1LqTbjrKcUgtJA
 
It has five 8255s, but one of those is for the clock interface.  I agree any new board we make would not need the real time clock part.
 
I am impressed with the versatility of the board and the three different ways they bring out the pin-outs for the parallel interfaces (DIP sockets, direct solder tabs, and .1” headers).  I fabricated a ribbon cable that connects two 14-pin DIP connectors to a “PC style” parallel cable (DB25 to Centronics).  I agree with Joe that we should have multiple ways to bring the parallel ports out depending on what people want to use it for.  Here are my notes on how I set up the Centronics interface.
 
 
H8-8255A-I-O-Schematics.pdf

Norberto Collado

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Oct 19, 2020, 2:43:31 PM10/19/20
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Mark,

I realized that it was for the H89-SCS board. Can you share the schematics for the PC89 board?

Thanks,
Norberto
-------- Original Message --------
Subject: RE: [sebhc] H8 PC-12 8255 I/O card
From: "Norberto Collado" <norberto...@koyado.com>
Date: Sun, October 18, 2020 11:07 pm
To: "se...@googlegroups.com" <se...@googlegroups.com>

Mark,

Ken shared with me the PC89 information to developed the H89 Parallel board.

Please check the website to find out what we are missing.


Thanks,
Norberto
-------- Original Message --------
Subject: Re: [sebhc] H8 PC-12 8255 I/O card
From: Glenn Roberts <glenn.f...@gmail.com>
Date: Sun, October 18, 2020 12:02 am
To: se...@googlegroups.com

Great!

Sent from my iPad

On Oct 17, 2020, at 11:11 PM, Mark Garlanger <garl...@gmail.com> wrote:


I have an H89 with the Environmental Control Systems PC89, and I think I have manuals and some disks for it.

Mark

On Sat, Oct 17, 2020 at 9:18 PM Norberto Collado <norberto...@koyado.com> wrote:
<image001.png>
 
Unfortunately, I have only the board itself, not the “extensive documentation and support software” ☹  However it was easy to set this up as a CP/M parallel printer by adapting a BIOS (I think I got this from Ken?) for the “2/3rds H89 serial/parallel board” from Secured Computer Systems.  Don’t think I ever built an HDOS driver (?) but again probably pretty straightforward.
 
Here are pictures of the board
 
https://photos.app.goo.gl/CUD1LqTbjrKcUgtJA
 
It has five 8255s, but one of those is for the clock interface.  I agree any new board we make would not need the real time clock part.
 
I am impressed with the versatility of the board and the three different ways they bring out the pin-outs for the parallel interfaces (DIP sockets, direct solder tabs, and .1” headers).  I fabricated a ribbon cable that connects two 14-pin DIP connectors to a “PC style” parallel cable (DB25 to Centronics).  I agree with Joe that we should have multiple ways to bring the parallel ports out depending on what people want to use it for.  Here are my notes on how I set up the Centronics interface.
 
 
<image002.png>
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Glenn Roberts

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Oct 19, 2020, 3:44:08 PM10/19/20
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Terry:  Your work is truly amazing and what an awesome setup!  Congrat’s.  I personally find the intersection of “old” and “new” technology a fascinating aspect of this hobby.

 

 

I don’t think I’ve seen anything before now on your system.  Would you be willing to share some of the details and code?  Particularly intriguing is how you’ve used the parallel board to connect the I2C world to the H8 – opens up a world of possibilities!

 

If you like I could help document some of this if you’ll share some of the details.  Perhaps some of us could then replicate your fine accomplishments…

 

  • Glenn

 

 

image001.png

Glenn Roberts

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Oct 19, 2020, 3:55:19 PM10/19/20
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Cool.  Love the I2C capability!

image001.png
image002.png

Terry Smedley

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Oct 19, 2020, 5:43:04 PM10/19/20
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Glenn:

Happy to share anything that I have done!  I confess that the flurry of activity around my H8 is pandemically-induced.  When the stay-at-home orders came, I had to find something to do.  I've had the H8 since introduction, but until COVID-19 it was a once-a-month exercise at best - to turn it on and see if the thing still worked. 

I enthusiastically agree that mixing up the old and new is very interesting.  Most of what I've done on the H8 parallels what I have been doing with the HERO-I robot - to teach it some new tricks using technology that wasn't around when it rolled out of Benton Harbor almost 40 years ago now.   After seeing my mods to the H8 and HERO-I, some of my tech-friends have asked, "Why don't you stick a $20 Arduino in there and be done with it?".  Well of course that misses all the fun.  No challenge, and little personal reward, for plugging in an Arduino.

The 8255->I2C connection was simpler than I thought it would be.  I found an old (ancient?) application note from Maxim that described a way to use a Centronics port to bit-bang I2C.  It's Maxim app note 3230, that is attached.  The hardware approach uses a 74HC05 (open collector outputs) to solve the issue of in/out contention on the Centronics or 8255 lines.  That's the extent of the hardware - a single HC05.  Well, OK, there is also a voltage level shifter so the H8 can cross the bridge to 3.3v devices.

With hardware in hand, I wrote pretty simple code - vanilla 8080 opcodes - for the unit operations of I2C:
  START
  STOP
  ACK
  NACK
  SEND ONE BYTE
  RECEIVE ONE BYTE

With those completed, it was just a matter of gluing them together in appropriate sequences to perform I2C READS and WRITES.   I found a terrific "I2C Primer" from Texas Instruments that really helped me understand what I was trying to recreate (Application Report SLVA704, also attached).  I will post the code (which is encapsulated in an HDOS .ACM file).

Because it's bit-banged, it's much slower than a dedicated hardware implementation.  I expected that the slow speed, which is variable because I didn't want to turn off interrupts, might cause a problem with some devices.  But every device I've thrown at it has accepted the poor man's I2C transmission just fine.  Not to say there aren't some devices that will be fussier, but it's worked fine with temperature sensors, ADCs, LCD and LED displays, and PWM servo controllers.  Sensor readings typically involve just a couple of bytes transmitted and received, so the slow speed hasn't proven to be a difficulty.  Hats off to Philips for developing a protocol that is so accommodating.

The photo that's attached is an example of a prototype board that plugs into the PC-12 8255 card and has 4-pin connectors for up to five I2C devices.  The same board is used in the HERO robot to give it I2C capability.

Terry

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AN3230.pdf
slva704.pdf
H8_I2C_board.jpg

Mark Garlanger

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Oct 19, 2020, 7:44:27 PM10/19/20
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I'll look for it, but I'm not sure there was a schematic with it. I don't remember seeing one with the docs.

Mark
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