PDP11 - LSI11/02 and RQDX3

[jlang]

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

I boot a RQDX3 using ODT. The MSCP boot code is 65 words.
I can't find the code online at the moment. I know it's out there...

 

[daver2]

I guess it is similar to what I have just located. In that case, I don't need to do any work if we can find it!

Dave

 

[jlang]

I have been looking around for DU-device boot ROMs.

Unfortunately, the only ones I can find are 16KW - and your bootstrap board only has 4KW of EPROM space by the looks of it.

I also haven't been able to find any source code (other than the file I found - but that is not a true bootstrap) for a stand-alone DU bootstrap.

I could try and build a set of bootstraps for our own PDP-11 software and see how small I can get it - but (from what I remember) you need an MRV11-C or an MRV11-D to hold it.

Somewhere, I have the MSCP protocol manual. I am going away on a business trip in a couple of weeks - A DU bootstrap would be a useful project whilst sitting in the hotel!

EDIT: Online at: https://vt100.net/dec/aa-l619a-tk.pdf.

Dave

I figured out where I got the MSCP boot. I ripped it out of SIMH.
SIMH boots by loading a bootstrap image into memory then executing it. So that image can be loaded via ODT

 

[daver2]

I was going to look at SIMH but didn't get around to it...

Good spot.

Dave

 

[spiceminer]

I figured out where I got the MSCP boot. I ripped it out of SIMH.
SIMH boots by loading a bootstrap image into memory then executing it. So that image can be loaded via ODT

That sounds great! Thanks for digging.... in case we speak really only about around 65 words this should be even compatible to my ROM board (which has 2kW capacity).
Looking forward to!

 

[spiceminer]

Lessee...if you switch an MXV11 for the DLV11, you get a console port and sockets for boot ROMs, as well as some memory. As far as a bootstrap goes, how about this one? https://www.ibiblio.org/pub/academic/computer-science/history/pdp-11/bootstraps/mscp_rt11.txt

It would be long to toggle in, but could be burned to a ROM on the MXV11. Since it's MSCP, it should boot a floppy just like it would a larger disk.

These boards are not so easy to find these days. Assuming I would get my hands on one for an acceptable price, what will my non MMU system do whem there is additional kWords .... I already have a 32kW Ram board installed?

Thanks a lot for finding the link! You think that bootstrap will work out of the box or does this need some adaptation?

Regards
Stephan

 

[leegleason]

These boards are not so easy to find these days. Assuming I would get my hands on one for an acceptable price, what will my non MMU system do whem there is additional kWords .... I already have a 32kW Ram board installed?

Thanks a lot for finding the link! You think that bootstrap will work out of the box or does this need some adaptation?

Regards
Stephan

You can disable the memory on the MXV11, or remove the memory card and use the MXV memory. Another MXV advantage - it provides two DL11 ports, so one is the console and the other can be used with a TU58 emulator. I have a two card RT11 system in a BA11-VA, with an 11/02 processor and an MXV11 providing console port, memory, boot roms, and a TU58 port for storage. In any case, MXV or no, I'm pretty sure that boostrap will work. I haven't used it as a bootstrap, but have used most of it in a project I worked on to provide MSCP support. You would need to modify the instruction at START: to point to another unit number, if you aren't using unit 0.