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Is SCSI boot an option for PDP-11/53?

A

acollins22

Experienced Member
Joined
Mar 12, 2007
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Leicester, UK
Hello,

Thanks to the suggestions of members of this forum I am now able to get my recently acquired PDP-11/53 to boot from a PC emulating a TU58 into the XXDP utilities.

It was suggested that I look out for an MFM drive, ST-225, but they're not too easy to get hold of and I wasn't sure about a different MFM drive as in those days you had to specify cylinders, heads, tracks etc.

So, thinking laterally, I'm wondering if a SCSI card would be a good thing? I have a stash of SCSI drives. What about a KZQSA (M5976-AA)?

Would this be bootable and a good/bad idea?


Thanks,

Andy.
 
acollins22 said:
So, thinking laterally, I'm wondering if a SCSI card would be a good thing? I have a stash of SCSI drives. What about a KZQSA (M5976-AA)?

Would this be bootable and a good/bad idea?
Click to expand...

In general a Q-Bus SCSI controller is always a good thing, on either a PDP-11 or a VAX. I have a few flavors, CMD CQD-200, CQD-220, and CQD-220A, and Dilog SQ706A and SQ3706A. They can be used to boot an MSCP aware PDP-11 OS, or VAX VMS.

I also have an M5976 KZQSA. However with that one everything I have read on the net suggests it is really only good for booting a SCSI CD-ROM on a VAX, and that is all I have done with mine. It is not an MSCP compatible controller and I am not aware of any support for it on a PDP-11.

The M5977 RQZX1 is supposed to be an MSCP compatible controller but I have never seen one of those in person and don't remember seeing any on eBay. They might be somewhat rare compared to other Q-Bus SCSI controllers.

-Glen
 
Andy,

You can boot from SCSI, my 11/53 does, but I have a third party (andromeda scdc 11) card. These are pretty rare and you have to be lucky (like me) or willing to pay big money for a SCSI board. My SCSI card emulates the mcsp protocol, so the pdp thinks the SCSI partition is just a really big DEC drive. Emulex is another third party controller brand.

Be careful with the DEC SCSI cards - one I know is not bootable. They were also built for vax machines, so may not work for pdp's.

- Crawford
 
KZQSA is not useful in pdp-11 systems. The RQZX1 is the real dec qbus scsi controller that will work with 11 systems.

I use a CMD CQD220 to boot my 11/73 from scsi disks. It works fine.

As for MFM disks, you could probably try any disk you can find. However, ST225 is quite relaible. Many other disks by now will require some mechanical reconditioning due to stuck grease. As for the geometry, I have worked out a procedure, discussed in another thread, to patch the dec ZRQC?? XXDP RQDX3 MFM disk formatter to use disks of any geometry.

Lou
 
I'd like to add to Lou's thoughts and say that if you're at all inclined to leave open an MFM experimentation path for yourself, the controller to have is an RQDX3 and right now is the time to get them.

Once some industrious person realizes he can market a low cost MFM drive simulator from Reinhard's beginnings, these controllers will go through the roof in price.

Even now, Lou's put together enough of an experience base to use almost any real MFM drive with an RQDX3 by patching the formatter.

Just my 2 cents.
 
@ Crawford

Do you have docs for your Andromeda card? I've got one around here that I set aside a long time ago because I had no idea of how to set it up.


*************************************

@RSX -

I'm not quite willing to lay a side bet, but my guess is that "through the roof" pricing reflects attractiveness to current commercial users (CNC, etc.) and really isn't driven by hobbyist usage. I wouldn't suggest hoarding RQDX3 controllers as a retirement nest-egg. :>)

Jack
 
jackrubin said:
Do you have docs for your Andromeda card? I've got one around here that I set aside a long time ago because I had no idea of how to set it up.
Jack
Click to expand...

Docs for Andromeda cards seem scarce. I have an Andromeda ESDC Q-Bus ESDI controller that I never found any docs for. I think I was eventually able to figure out how to get into the on board config utility through its serial port. I don't remember the details on that now.

-Glen
 
@Jack (with apologies to Andy for hijacking his thread)

I did not find any docs for the Andromeda, but I did get a terminal hooked up to the SLU on the board and hacked through the menus. I can probably recreate what I did to get it running. It is a *very* nice board, we'll worth getting working.

@All,

Davis Gesswein is working on a MFM emulator using a Beaglebone Black board. No slight to the great work Reinhard has done, but Dave's solution seems to be both simpler and cheaper. I still like Lou's notion of replacing the disk controller chip on an rqdx3 to talk PATA rather than MFM. I've dumped the RQDX3 ROMs to look at the T11 code. We'll see..

? ; - )
 
Thanks folks,

It looks like MFM is the way to go. I didn't realise that we could be versatile with sectors/tracks etc. That makes life a lot easier.


Cheers,

Andy.
 
acollins22 said:
It looks like MFM is the way to go. I didn't realise that we could be versatile with sectors/tracks etc. That makes life a lot easier.
Click to expand...

Just a slight note, I think the sectors per track is always fixed at 17, while it is the number of head/surfaces and tracks/cylinders that are variable.

I believe that the VAXstation 2000 firmware formatter is supposed to be compatible with the RQDX3 formatter. I have never verified that myself. I have a VS2000 but lack the internal MFM cable set to give it a try.

Here is a page with some information on all of the VS2000 formatter parameters:
http://www.vaxarchive.org/hw/vs2000/fmtbob.html
 
gslick said:
Just a slight note, I think the sectors per track is always fixed at 17, while it is the number of head/surfaces and tracks/cylinders that are variable.
Click to expand...

Nope, I have the listings for ZRQC?? (all of them, including H0). Sectors per track is set in the tables in ZRQC. The RD51 is 18 sectors per track (in the tables), while all others are 17.

I took it all apart and wrote up exactly how to calculate parameters and patch ZRQCH0 for any geometry disk. There's an earlier thread on this.

Lou
 
Lou - N2MIY said:
Nope, I have the listings for ZRQC?? (all of them, including H0). Sectors per track is set in the tables in ZRQC. The RD51 is 18 sectors per track (in the tables), while all others are 17.

I took it all apart and wrote up exactly how to calculate parameters and patch ZRQCH0 for any geometry disk. There's an earlier thread on this.

Lou
Click to expand...

OK, that's interesting to know. Do you know whether the VS2000 firmware disk formatter is compatible with the RQDX3 disk formatter? Can you format with one and move the drive to the other?
 
jackrubin said:
A CMD CQD-200 just popped up on eBay for $200 - item 151246454462
Jack
Click to expand...

Now up to $230, although you could make an offer. Maybe the price goes up with the number of watchers?

I'm not sure what the /MJ suffix (instead of plain /M) means. If you have one of these that is not a /TM (MSCP and TMSCP) it can be converted to a /TM version by replacing the CSR decode PAL and the firmware EPROMs.

The PAL version on the eBay item 151246454462 is P20011A which is probably the MSCP only version.
PAL version P20010A is /TM (MSCP and TMSCP)
PAL versions P20012B and P20012C are /T (TMSCP only)
 
Pretty wacky - it was $199.99 BIN when I posted it. I should have bought it just to pass on!

Trying to interpolate from the manuals, I think the J suffix refers to support for jukeboxes (I would assume a tape cartridge robotic autoloader in this case); regardless since you have the prom codes, it could easily be re-purposed. It was a "hmmm...." at $199; at $230 it's getting toward a "mmmaybe..." but someone should just jump on it. 30 bucks is just a few trips to Starbucks and SCSI is forever.

Jack
 
$200 would separate a CMD CQD-200/TM (what it effectively is now, was originally a /T version) from me if someone really wants one and doesn't get the seller of eBay item 151246454462 to accept a lower offer.
 
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