PDP8M OS8 Monitor ERROR

[MauriceH]

As I have my PDP8M working so far , on that HowTo later.

If I boot from OS8_RX.RX1 disk with the RX02 emulator I get perfect the Boot DOT.
Then a DIR and indeed there is a Dir of the disk.
Second attempt I get a Monitor ERROR 3.

With a real RX02 FFD drive and a Bootdisk OS8 I get also the Boot DOT.
Then a DIR RXA0: I also get that ERROR:
Monitor error 3 handler at 00623 (DEVICE HANDLER NOT IN CORE)
Have 8K of Core.

I use a real VT220 at 03/04 in VT100 mode.
Use RX01 RX8 Boot with real RX02 in RX8 mode SW1=ON, SW2=OFF
What Handler am I missing?

 

[daver2]

Out of interest, which version release of OS8 are you using?

If a direct DIR (without a drive specifier) is working - then that should be using the default drive it was booted from.

I assume it is complaining about the device you have specified as RXA0:?

I have had some peculiarities with the drive specifiers before - but that was a long while ago and I think those braincells have died off now...

Dave

 

[djg]

OS8_RX.RX1 disk

Is this image online somewhere?

 

[daver2]

I suspect they are the ones here: http://www.pdp8online.com/ftp/images/os8/?

os8_rx.rx01

They seem to be referred to by this article: https://raymii.org/s/articles/Creat...om_RX01_floppies_for_the_PDP-8_with_SIMH.html

This image seems to have RXA0 and RXA1 configured and is RT-11 V3Q.

Dave

 

[daver2]

Booting from that image and invoking the commands:

.DIR
.DIR SYS:
.DIR DSK:
.DIR RXA0:

All appear to work OK.

Dave

 

[DougIngraham]

I could be confused but I think your problem is that you only have 8k. The RX02 OS/8 handler is a 2 page handler. As a SYS device a 2 page handler requires 12k. The first page of the system handler will reside on field 0 from 7607 through 7743. The second page of a SYS handler resides on the last page of field 2 from 7600 through 7777. If you only have 8k of memory you could get booted but it would not be able to read or write using SYS.

It looks like it boots because the boot code talks directly to the drive and does not use the handler. I don't understand why you are getting the monitor error messages. It seems like it should just crash.

You should be able to boot using it as an RX01 and install an RX02 non-system handler on an 8k system. You just won't be able to use the RX02 as a system device. The RX01 handler I have source code for fits exactly in one page and uses all the tricks to do so. The uncredited Author was very good. Of course you might not be using the DEC RX02 or RX01 handlers. I have heard that someone wrote a 2 page RX handler that uses the device in 8 bit mode. This gives you quite a lot more space on a diskette but can cause a lot of confusion.

The only other 2 page system device I can think of is for the TD8E (Simple DECtape controller.) That one will also require 12k to be used as a system device.

I have an RX02 that I have not tried to use yet so I don't know anything from first hand experience.

You could try to boot the image in a version of SIMH that is restricted to 8k and see if it behaves the same way.

 

[daver2]

Just changed my SIMH configuration from 32K to 8K and it still works.

.DIR
.DIR SYS:
.DIR DSK:
.DIR RXA0:

All OK.

There is no assumption within OS/8 (for later revisions) about the hardware it is running on is there? Thinking about instructions such as Byte Swap. I would have thought it unlikely, but it just popped into my head...

Dave

 

[DougIngraham]

There is no assumption within OS/8 (for later revisions) about the hardware it is running on is there? Thinking about instructions such as Byte Swap. I would have thought it unlikely, but it just popped into my head...

OS/8 itself was written to run on any Family of 8 machine which means they avoided using BSW or any of the operate combos that don't work on some machines. And although I don't know of anything I bet there was probably something that wouldn't work somewhere (Cough 8/s Cough Cough).

 

[daver2]

That's what I would have thought - but it popped into my head whilst I was doing the washing up so I thought I would put it out there...

Dave

 

[daver2]

It it possible to run RESORC /E to ensure that the RXA0 and RXA1 device names are actually present?

Dave

 

[MauriceH]

Thanks For the help.
Problem is in the Prototype version M847E with also ext MeM parts on it and partly disabled.
Maybe that is corrupting something.

I now use the real M847 with RX01 bootstrap and works as a charm.
See attached Photo with the Build Handlers and OS8 version I use.Disk OS8_RX.RX1
That works fine now.

The BASIC on the disk OS8_RX.RX1 is defect somehow.
So with the RX02 EMULATION (Arduino) attached to M8357 card and Booted from
an other disk with BASIC on it.
I could enter a working BASIC Prog with the PDP8/M.

After 10 Yrs of having the PDP8 Now Finally after lost of struggles manage to get it to work.
What a great Success.
Look at the 2nd Photo!

 

[daver2]

Sweet !

Dave

 

[DougIngraham]

Very nice!

 

[tradde]

Congratulations.

 

[jackrubin]

Good news, thanks for sharing the journey with us!