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OS8 Disk Server Console TTY Baud Rate

N

NicolasF

Experienced Member
Joined
Jun 28, 2006
Messages
255
Location
Argentina
Hi,

I would like to boot the machine using the OS8 disk server program but I'm not sure how to set the console TTY baud rate.
Where are these settings located?

Thanks!
 
Just for the avoidance of doubt - which console baud rate are we talking about?

You would normally run the OS8 serial disk server on a second serial port on the PDP8 - so the baud rate of the PDP8 second serial port and the OS8 serial disk server need to agree. No 'console' involved?

Dave
 
I have two M8655 boards configured like this:

1- Dumb Terminal (Console TTY) Receive 03, Transmit 04
2- OS8 Disk Server (Second TTY) Receive 40, Transmit 41

I'm not sure how select the baud rate, bits, stop bits, etc for the first one (Dumb Terminal). I know that configuration for the second one (OS8 Disk Server) is defined in the "disk.cfg" file.
I could not find anything about this configuration in the OS8 Disk Server project, maybe this is defined somewhere in OS8? I'm guessing there has to be some default settings.
 
From my understanding the M8655 baudrates are set by physical switches/links on the card itself.

The disk.cfg file sets the serial port speed for the computer running the os8 serial dis server itself, not the M8655 to which it is connected.

The baudrate configured into disk.cfg and that configured on the Omnibus card must agree (as must parameters such as the number of data bits, the parity and the number of stop bits).

Dave
 
I run my “dumb” terminal at 9600 baud using Putty. I also have used TerraTerm (sp?) and Simple Term successfully. I’ll check bits, stop bits, parity, etc. when I get home tomorrow. I have not had success with higher baud rates, not sure why... 9600 seems fine, as the baud rate for the SerialDisk server seems the more important to have as a high baud rate, since it is accessing the disk file frequently..

Key info on settings for the M8655 can be found on the University of Iowa website - again, I’ll find the exact link tomorrow. It is a great site for board baud and address settings as well as ways to increase the baud rate for your board running DiskServer.

One thing you might consider is building Roland Huisman’s Extended Bootloader board or Vince’s combo bootloader and memory board to simplify the process of loading SerialDisk and other common boot programs.

Regards, Matt
 
>>> My question is about what baudrate should I use for the dumb terminal, is it 9600, 110?

I see now.

The problem is that the PDP-8 / OS8 doesn't use handshake signals on the serial lines. This means you can 'push' the baudrate a bit and it will work OK. Push it further, and it will fail. You will have to find this point yourself from your particular configuration. The slower the speed, the more resilient it will be. As you push the envelope, you may start to get failures.

This is just a fact of life I am afraid. With equipment that is this old what works for one machine may not work for another.

Dave
 
It's possible to run OS/8 DiskServer up to 115200 baud if you have a KL8E (M8650), some modifications needed though: https://www.pdp-9.net/configure-m8650-kl8e-for-serialdisk

This is not possible with the KL8JA, there the actual UART circuit limits the maximum speed. I just got 9600 as max when I ran with M8650. There is no UART chip on the M8650

Short cables and correct grounding is recommended when higher speeds are used.
 
As a follow-up to my note from yesterday, I run Kyle's SerialDisk with a M8650 modified as per the link in anders_bzn's note to achieve 115200 baud and disk.cfg set for 2 stop bits. Addresses set to 40/41.

My PuTTY session for the "dumb terminal" runs on a M8655 at 9600 baud, 7 data bits, 1 stop bits and no parity. Addresses set to 3/4.

The link to Douglas Jones' great University of Iowa site is in djg's note from yesterday.

Regards, Matt
 
Today I tried booting the machine but it didn't work. I had the M8655 server board configured as 19200-8-N and 2 stop bits (SB and W4 removed).
The console M8655 is 9600-8-N 1 stop bit. On the OS/8 server disk I only get the "Booting..." and "Done sending block 0".
The pdp keeps running but it doesn't seem to be sending anything to the server so it just keeps waiting.
I noticed that the first EMA light turns on and I checked this video:

https://www.youtube.com/watch?v=9qHrEkjavUc

And the light never turns on, I have no idea how to find the problem, any ideas? :confused:
 
NicolasF said:
Today I tried booting the machine but it didn't work. I had the M8655 server board configured as 19200-8-N and 2 stop bits (SB and W4 removed).
The console M8655 is 9600-8-N 1 stop bit. On the OS/8 server disk I only get the "Booting..." and "Done sending block 0".
The pdp keeps running but it doesn't seem to be sending anything to the server so it just keeps waiting.
I noticed that the first EMA light turns on and I checked this video:

https://www.youtube.com/watch?v=9qHrEkjavUc

And the light never turns on, I have no idea how to find the problem, any ideas? :confused:
Click to expand...

From the KL8JA notes document:
Code: 
A zero ohm resistor or wire jumper should be inserted at either W2 or
W5, but not both. This selects the highest baud rate the board will
support.

	W5 (left) - 19200 baud
	W2 (right) - 9600 baud

The original GI UART could only handle 9600 baud; the SMC COM 2017 UART
used on later boards can handle either baud rate.

So it mainly depends on what UART device is in your board. It is the large 40p device.

All versions of M8655 should work at 9600baud; I would recommend going with that rate to start.
 
Set the M8655 as one (1) stopbit and 9600 baud. You could then try with one or to stopbits in the serial disk configuration. First try try to connect the board to a serial port won a PC and start a serial console and verify that you can get charters true.

First try:

Code: 
//   03/04 40/41
0: 7001
1: 6046   6416
2: 6041	  6411
3: 5002
4: 5000

The a simple echo program
Code: 
//Echo on terminal
//   03/04 40/41
201: 6032  6402 
202: 6031  6401
203: 5202
204: 6036  6406
205: 6046  6416
206: 6041  6411
207: 5206
210: 5202

If this doesn't work, try to measure the output from the M8655 with an oscilloscope if you have one.
 
AK6DN said:
From the KL8JA notes document:
Code: 
A zero ohm resistor or wire jumper should be inserted at either W2 or
W5, but not both. This selects the highest baud rate the board will
support.

	W5 (left) - 19200 baud
	W2 (right) - 9600 baud

The original GI UART could only handle 9600 baud; the SMC COM 2017 UART
used on later boards can handle either baud rate.

So it mainly depends on what UART device is in your board. It is the large 40p device.

All versions of M8655 should work at 9600baud; I would recommend going with that rate to start.
Click to expand...

I left W5 shorted and W2 open to set it to 19200. I also checked the IC and it´s SMC COM 2017.
 
anders_bzn said:
Set the M8655 as one (1) stopbit and 9600 baud. You could then try with one or to stopbits in the serial disk configuration. First try try to connect the board to a serial port won a PC and start a serial console and verify that you can get charters true.

First try:

Code: 
//   03/04 40/41
0: 7001
1: 6046   6416
2: 6041	  6411
3: 5002
4: 5000

The a simple echo program
Code: 
//Echo on terminal
//   03/04 40/41
201: 6032  6402 
202: 6031  6401
203: 5202
204: 6036  6406
205: 6046  6416
206: 6041  6411
207: 5206
210: 5202

If this doesn't work, try to measure the output from the M8655 with an oscilloscope if you have one.
Click to expand...

Yes I tried both 1 and 2 stop bits and I get the same thing. I did test the board with the echo program and it was working fine. I'll do that same test again and I'll connect an oscilloscope.
I have built the "Minimal RS232 cable KL8-E to 9-Pin DTE Device" from this website: http://avitech.com.au/?page_id=1628 is that ok?
 
Going back to your post #10 you were stating that the server sent the boot block and then one of the EMA lights came on.

For the server to send the boot block it has to have seen the '@' character from the PDP.

If it sent the bootblock to the PDP (and this was stored correctly) then the PDP should have tried to execute the bootstrap. This seems to be where things go wrong.

I would get a slow pair of serial ports running reliably with the echo program (both the console and the serial server line) - change the IOT instructions in the echo program to test the second serial line.

Then see what happens when you try the PDP bootstrap with the serial server.

Dave
 
There is one step from the how-to.md guide that I did not do, and that is "### INSTALLING THE SYSTEM HANDLER ###" (no idea what system handler is and what it does).
I assumed that thing is already installed in the diagpack2.rk05 provided in the zip os8diskserver file that you download from the github project. Could this be the problem?
Is there anyway I can check if that thing is installed in the image?

Thanks!
 
The system handler is the thing that OS/8 uses to talk to the default boot disk. If you are using an RK05 image, OS/8 will try and talk to the RK05 drive that it was configured for.

The system handler gets replaced so that the OS/8 operating system can now talk to the serial server.

If it hasn't been replaced on the image you are using, it will not work.

What does the 'readme' file say to do?

Dave
 
Hello Nicolas,

what you are writing seems to be OK.
I started with two cards, same speed. Just different addresses. I tested both cards with the echo test and loading FOCAL with RIM and BIN loader.
After this I was shure, both cards are working.

Than I set up os8diskserver, exactly like in the tutorial.
It worked spot on.

The only thing I observerved was, that when loading the os8bootloader, I always got the leftmost Bit in AC high.
But controlling the bootloader, every Byte was OK. I had this on 3 machines. I compiles the bootloader with palbart, always the same. This is still open for me.

Meanwhile I change the speed of the terminal seriel line from whatever I need. Depending on using my ASR-33 current loop or any terminal-program (RS232) on my raspberry (kermit, minicom).
My cables are like in the link you send.

If you are using the M8655, it is easy to change the address of the cards, did you swapped them and get the same results?
What messages do you see from the os8diskserver on the console window?

Best regards
Volker
 
Ok, I just tried it again and same result. Server hangs on "Done sending block 0".
I tried the following:

1- Echo program on both cards (OK)
2- Change bauds to 110 on both cards (OK)
3- Installed "system handler" on the original diagpack image (no change, server still hangs)

I guess I'm having some memory issues so I tried to run a memory test but I'm not sure if it worked or not.
I'll create a new thread to see if I can get some help with the memory test.

Thanks!
 
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