Looking for refresher on Heathkit H8-4 Serial Ports and common usage

[Eric Mack]

The last time I worked with this Serial board was probably 40+ years ago when I built my H8.

 

The H8-4 Serial Card has four ports 0-3

 

My terminal (H19) is connected to Port 0

 

I also have an H-14 Printer and my trusty Hayes Modem

 

I’m guessing (and here’s where I am asking for help) that the Printer would be Port 1 and the modem on Port 2. If I recall, I used to be able to press CTRL-P in CP/M and it would echo to the printer.

 

IF I have the above correct, then my plan would be to dedicate the fourth port (port 3) to a serial cable connected to my PC for file transfers, like this

 

Port 0    Console (H19)

Port 1    Printer (H14)

Port 2    Model (Hayes)

Port 3    Serial Cable with null modem crossover to PC for file transfer

 

 

Thanks in advance.

[norberto.collado koyado.com]

Yu need to define the port number for each channel:

 

For sure, we have one port configure for the H19 and that is 350Q. For the modem it needs to be on port 330Q. For the other two, I will let Joe define such ports.

 

Port 0    Console (H19) (350Q) and working

Port 1    Printer (H14) (TBD)

Port 2    Model (Hayes) (TBD)

Port 3    Serial Cable with null modem crossover to PC for file transfer (330Q)

 

Norby

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[Glenn Roberts]

So any of the four channels can be used for any purpose. What matters is the port numbers and interrupts assigned via the jumpers. The assignments you list are typical of how most users set up their channels I believe.

With the h8-4 you should never need an external crossover (“null modem”) cable as you can specify for each channel whether it is to appears as Data Communication Equipment (DCE), or Data Terminal Equipment (DTE). In any serial communication setup one device must be DCE and the other DTE. Each channel has two sets of 15-pin headers. Connect your interface cable to the upper header to create a DCE connection and the lower for DTE.

For the console set the port jumpers for 350Q, install the interrupt jumper on IRQ3 and connect the cable to DCE (since the H19 or other terminal will be DTE).

For the H14 the convention is to use port 340Q. I don’t believe printer software typically uses interrupts (?) so you probably can leave the IRQ jumper in the OFF position. Unfortunately manufacturers were not consistent in deciding whether printers were DCE or DTE. I don’t know if the H14 is DTE or DCE so consult the manual or just do trial and error. I think printers most often were DTE so set the h8-4 port to DCE and try that.

For the Hayes modem you would typically use port 330Q. Since a modem is DCE you would need to configure the port as DTE. I think most comm software took advantage of interrupt processing but am not sure. You’d have to check based on what package you plan to use. Typically this would be IRQ5.

If you plan to connect to a PC to use Xmodem file transfer you probably should not connect the modem as you’ll need port 330Q for this. Generally speaking the ports on PC serial connections are configured as DTE (on the assumption that the PC is used to emulate a terminal) so typically you would configure the h8-4 port as DCE.

The fourth port could be configured as port 320Q if need be. This was most often used for a second printer (e.g. letter quality “Diablo” printer) or a plotter. This typically required you to set up a custom driver configuration in the OS.

Joe Travis knows this stuff inside and out an I’m sure he’d be happy to answer any questions once he’s online…

Sent from my iPad

On May 15, 2025, at 2:59 AM, 'Eric Mack' via SEBHC <se...@googlegroups.com> wrote:



--

[Joseph Travis]

It really doesn't matter which channel is assigned to what port.  The port assignments (by the book) are:
350Q - console terminal
340Q - printer
330Q - modem
320Q - alternate terminal

Joe

To view this discussion visit https://groups.google.com/d/msgid/sebhc/259CA79C-37EB-493B-8C6A-6252362D97FF%40gmail.com.

[Joseph Travis]

'Sorry... What I neglected to mention is that if you plan to transfer files between the H8 and a PC, you'll want to connect the PC to the modem port (330Q) to use a terminal program such as MAPLE for XMODEM tranfers.  BTW - MAPLE only uses checksum mode, not CRC.

Joe

[norberto.collado koyado.com]

Thanks Joe!

To view this discussion visit https://groups.google.com/d/msgid/sebhc/CAGQDgBD%2B%2BLp%3DnUMW1ACp%3Dt6CLQjoUoRNy2A%2BcEbF7vtCJ59i-Q%40mail.gmail.com.

[Eric Mack]

Thank you, Joe. I found the MAPLE software on the CF card; however, I’ve been unsuccessful at finding and documentation on-line, now was I able to figure out how to do little more than start or end a session. 😊

 

Can you or anyone point me to any MAPLE documentation, if it exists?

 

Ideally, I’d like to find an example of how to set up a session, specify the I/O port and speed, and initiate a transfer.

 

I’m pursing MAPLE because you mentioned it, but I am open to other solutions as well.

 

Thanks in advance.

 

Eric

From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of Joseph Travis
Sent: Thursday, May 15, 2025 5:38 AM
To: se...@googlegroups.com
Subject: Re: [sebhc] Looking for refresher on Heathkit H8-4 Serial Ports and common usage

 

'Sorry... What I neglected to mention is that if you plan to transfer files between the H8 and a PC, you'll want to connect the PC to the modem port (330Q) to use a terminal program such as MAPLE for XMODEM tranfers.  BTW - MAPLE only uses checksum mode, not CRC.

To view this discussion visit https://groups.google.com/d/msgid/sebhc/CAGQDgBB2EHMfRo6vgzm9hsz52YQguLOVScwqPM0qo2_RptnCYA%40mail.gmail.com.

[norberto.collado koyado.com]

It is here:

 

https://koyado.com/Heathkit/Z67-IDE_HDOS_CPM_files/MAPLE_CPM.pdf

 

Norby

To view this discussion visit https://groups.google.com/d/msgid/sebhc/PH0PR13MB5999F1B876DAE84FC530C5398193A%40PH0PR13MB5999.namprd13.prod.outlook.com.

[Joseph Travis]

Thank you Norberto!

To view this discussion visit https://groups.google.com/d/msgid/sebhc/SA3PR01MB791807AFC0414D5AAC84789EF793A%40SA3PR01MB7918.prod.exchangelabs.com.

[norberto.collado koyado.com]

This is Ken Owen page and there is more information there. Here is the link to the main page:

 

https://koyado.com/Heathkit/Z67-IDE_HDOS_CPM.html

 

Norberto

To view this discussion visit https://groups.google.com/d/msgid/sebhc/CAGQDgBBHh-uGt-A5D%2B_thS7yL3KHMUUcJZaXaZW5t1CQBC5ccw%40mail.gmail.com.

[Steven Hirsch]

On 5/16/25 14:04, norberto.collado koyado.com wrote:
> This is Ken Owen page and there is more information there. Here is the link to
> the main page:
>
> https://koyado.com/Heathkit/Z67-IDE_HDOS_CPM.html

> <https://koyado.com/Heathkit/Z67-IDE_HDOS_CPM.html>

Is Ken still with us? Haven't seen any postings from him in several years.
Hope it's just a matter of shifting interests.

[Glenn Roberts]

I spoke with Ken not too long ago. I believe he’s in his late 70s now and realizes he needs to find new homes for his collection. I think he tried a few times to get back into the hobby but found it too difficult. I offered to help however I can. He was going to assemble an inventory list. I’ve sent him a few follow up emails but he hasn’t responded. I will give him another call.

Sent from my iPad

> On May 18, 2025, at 12:04 PM, Steven Hirsch <snhi...@gmail.com> wrote:

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[norberto.collado koyado.com]

The last time I email Ken (years ago), he was having difficult with his eyes. It was hard to see at such time. ☹

 

-----Original Message-----
From: se...@googlegroups.com <se...@googlegroups.com> On Behalf Of Glenn Roberts
Sent: Sunday, May 18, 2025 9:18 AM
To: se...@googlegroups.com
Cc: se...@googlegroups.com
Subject: Re: [sebhc] Looking for refresher on Heathkit H8-4 Serial Ports and common usage

 

I spoke with Ken not too long ago. I believe he’s in his late 70s now and realizes he needs to find new homes for his collection. I think he tried a few times to get back into the hobby but found it too difficult. I offered to help however I can. He was going to assemble an inventory list. I’ve sent him a few follow up emails but he hasn’t responded. I will give him another call.

To view this discussion visit https://groups.google.com/d/msgid/sebhc/5EF62FA9-3D45-4931-B6C7-96A679E9F4F8%40gmail.com.