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PDP11 - LSI11/02 and RQDX3

S

spiceminer

Experienced Member
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Mar 8, 2014
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205
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Europe
Dear All,

I currently try to restore a system with KD11-HA CPU and additional 32kW RAM Card MSV11-D in a dual width backplane and a lot of questions, as this is my first PDP-11.

I am a starting with storage....
Is there a possibility to operate a MFM harddrive and 5.25" RD50 disk drives together with a RQDX3 Controller?
1711616595901.png

1711616627244.png

Thanks a lot
Stephan
 
Welcome to the world of PDP-11 machines...

I wouldn't start with storage just yet. I would get the CPU, memory and bootstrap working first. Then move on to storage - but you can still ask the question!

You should be able to get the CPU working on its own (without memory) with just a console port for ODT. It won't do a lot (!) but it will demonstrate that the first step is working...

Then add memory.

Then add storage.

The first thing is to thoroughly document the link, wrap and switch settings you have on your cards. Take a high resolution photograph and start a notebook with the settings documented.

Then, download the manuals from Bitsavers for the cards and backplane. Check that they are ALL configured correctly for either 16-bit, 18-bit or 22-bit operation (depending upon what backplane you have and whether it has been modified to contain the additional address lines of it is (say) a 16 or 18 bit backplane.


The above manual states that you should be able to drive 2 hard and 2 floppy drives from an RQDX3 - but you may require an RQDXE expander. This all depends upon what chasses you have...

Ask away...

Dave
 
Dear @daver2!

Thanks a lot for your reply. The first step is already done.

Using a M8043 DLV11 4x serial card and the wire wrap settings done correctly, I get the ODT console and it seems to work. The Backplane is not an original DEC one. I read "Transduction" and "made in Canada" on some of the parts...

1711622726669.png

1711622598580.png
 
...As the system is LSI-11/02 I suppose the backplane is configured to 16 bit - Do you know how I can verify this?

Reading the RQDX3 manual I am unsure if it will work on my older system as RQDX3 is made für MicroPDP and MicroVAX Systems....
 
The bottom line is it may be dictated by the CPU card.

If the CPU card is ONLY 16-bit, then it doesn't matter what the backplane is...

The RQDX3 is 'supposed' to work with a 16-bit backplane. Whether it does or not I will need to check.

1711624722333.png
Dave
 
@daver2 Likely the most difficult task is to bootstrap the system. I suppose there is no "auto boot" from RQDX3 so keying in the bootstrap using ODT may be needed?
 
Unless you have an MRV11-C (or similar) board to store some bootstrap firmware - yes, you are going to have to enter it via ODT.

PDP11GUI can do this automatically for you, as can a terminal emulator acting as a fast human!

But both of these solutions require some sort of external PC of some description (or a Pi or similar).

Dave
 
daver2 said:
Unless you have an MRV11-C (or similar) board to store some bootstrap firmware - yes, you are going to have to enter it via ODT.
Click to expand...
I assume the board below would be suitable...

Do you have an idea what ODT commands would be needed to bootstrap from RQDX3 (or where to start reading to figure this out?)
Thanks
Stephan
1711631271944.png
 
Very probably.

You should be able to dump the code - it should appear at 173000 (in a 16-bit system with a following wind).

I should be able to find a barebones RQDX3 bootstrap for you from somewhere...

Have you looked in the RQDX3 manual?

There may already be the bootstrap in there. Failing that, we have to use the manual to figure out how to load the first track and first block into memory (at what address) and execute it.

There should also be the barebones bootstrap code already in other DEC bootstrap chips that we should be able to 'steal' and butcher...

Dave
 
spiceminer said:
@daver2 Likely the most difficult task is to bootstrap the system. I suppose there is no "auto boot" from RQDX3 so keying in the bootstrap using ODT may be needed?
Click to expand...
I use minicom as a terminal for a PDP-11/2. I wrote a small program that minicom calls that sends The bootstrap to ODT (with delays)
You will get tired of typing the bootstrap real fast.

The RQDX3 will work in a 16 bit backplane.
 
Still struggling with my effort to initially boot my LSI11/02.

My Basic Idea: Hook up a 5.25" Floppy Drive to the RQDX3 - Write an Image with Dunfield's Image Disk - Toggle in the right ODT bootstrap.

Would this be a good idea? Anyhow, I cannot find references to diskette bootstraps on PDP11 using RQDX3... Any suggestions? In the manual there is nothing and I my assembler skills are unfortunately not sufficient enough to understand the code posted above https://github.com/rust11/rust/blob/master/p/drs/dup.mac

Thanks a lot
Stephan
 
It is quite intricate code and would take a while to strip out the relevant parts.

We probably need to look for something simpler..

Dave
 
daver2 said:
It is quite intricate code and would take a while to strip out the relevant parts.

We probably need to look for something simpler..

Dave
Click to expand...
Strange that there is so little to find in the internet about bootstrapping RQDX3 from PDP11 - I would guess this was a quite popular setup mid 1980s....?
 
The trouble is that there is much more to the MSCP protocol than a simple bootstrap I am afraid.

You wouldn't just enter an RQDX3 bootstrap via ODT I am afraid - hence the more complex bootstraps ended up in CPU bootstrap EPROMs.

Dave
 
daver2 said:
The trouble is that there is much more to the MSCP protocol than a simple bootstrap I am afraid.

You wouldn't just enter an RQDX3 bootstrap via ODT I am afraid - hence the more complex bootstraps ended up in CPU bootstrap EPROMs.

Dave
Click to expand...
I see. I do have an EPROM card (as depicted above), so in case such code would we available somewhere as EPROM image....

Or would it be more easy to boot the machine from another media and than hand over to RQDX3?
 
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