PDP-11 disks - what are people using?

[erd]

Given the growing discussion of Unibus SCSI over in the "Wanted" section, I thought I'd maybe try and drag it over here...

I have a wide variety of PDP-11 cabinets and CPU boards (a DataRAM 11/23 clone, a Heath H-11, Professional 350s, a Professional 380, 11/20, 11/05, 11/04, 11/03s, 11/23s, 11/23+s, 11/24s, 11/34s, 11/44, 11/70s), but relatively few disk controllers.

The "modern" machines all have RQDX3s or, in the case of the Pros, the CTI-bus equivalent. I collect ST-225s and ST-241s when possible, but unless I run across an RD53 or RD54, those systems are somewhat limited. The older machines have either an RL11, RLV11, RLV12 or, in a few cases, an RK11 or RKV11. Again... not much room.

An RD54 is enough room to play with on a Qbus PDP-11, but that leaves the Unibus machines out in the cold (the 11/70s have MASSBUS disk and plenty of it - if only I had the power in the quonset hut to spin a rack of Fuji Eagles).

So... with all of that intro... what Unibus disk interfaces are people using for machines in the 11/24 and 11/44 class? Some model of Emulex SMD controller? An RH-11 with DEC RM or RP disks? UDA-50 w/SDI disks? Home-built IDE?

-ethan

 

[tradde]

pdp-11 disk drives

pdp-11 disk drives

My 11/84 has the UDA controller, but I have no hard drives for it. This system should work, as it was a spare for some place and never used. It's in excellent conditon. I have yet to get the cable to hook up the console, but it will boot up to a point where it is waiting for console input.
My 11/34a will have the RL02 drive that I have. Once again I do not have a bootable pack. And I am not quite sure the RL02 even will load the heads. Still working on that one.
Tim

 

[erd]

UDA-50 and RL-11

UDA-50 and RL-11

Tim,

re UDA-50:

I have used a variety of SDI disks with the UDA-50 (and KDB-50 on my 8200). I can recommend looking for something that is more reliable than an RA81 (and lighter!). With a 30A surge at startup and 8A steady draw, you don't want to have a rack of three of them running for very long.

I haven't tried to hook them up yet, but I did get a pair of RA70s a little while back. Not sure about how to mount their front panels, or if I can just ignore them and use jumpers.

I've heard a lot of hobbists have RA90s and the like. Medium sized, large capacity and a good compromise if you need SDI storage. Never had one myself, but I've only ever seen one fail in years of use. If anyone reading this has any dead ones, I'm curious what the part number is for the alphanumeric LED status display... I'm looking for a handful of DL1416s to restore a 6502 micro, and the required part resembles what's in the frontpanel of an RA9x drive.

re RL-11:

Do you have any RL02 packs at all? The nice thing about them is, unlike the RK05, there's only one pack, no matter if the host is 12-bit, 16-bit or 32-bit (I don't think there's a 36-bit RL interface). If you have access to a Unibus VAX, it's trivial to make and restore image files to an RL02 pack under VMS or UNIX. You could also put the RL controller in the 11/84 (once it's running) and do the same under 2.11BSD.

What OS did you have in mind for the 11/34a? We used to run RSX-11/M 3.x and 4.x on ours. I think it's a little under-powered for RSX-11/M+ or RSTS newer than about v7. We tended to leave those tasks to the 11/24 with two to four RL02s. RT-11, of course, won't make an 11/34 break a sweat.

There's probably a way to use the 11/84, the RL-11 and the virtual tape software commonly used in recent times to bootstrap 2BSD to get an image on an RL02 pack. I think it's already been mentioned on ClassicCmp, but I'm pretty sure that the RL02 won't load heads unless it is up to speed (and the rotation sensor is working) and attached to a live controller (and terminated). It wants the world to be perfect before risking its heads.

Don't forget to lower the head lock on the RL02 before mounting a pack.

-ethan

 

[tradde]

My pdp-11 packs

My pdp-11 packs

I have exactly one RL02 and one RL01 pack. I also have one of each drive. I believe I can get more if I need these. For the 11/34a I had thought maybe RT-11. But I am not sure with the Mentec licensing thing.
I will have to see what I can do. Maybe a specific revision level is allowed.
I will probably run BSD on the 11/84. I tried the RL02 connected to the 11/34a. I never heard or felt the heads load. It was terminated correctly as far as I know. My M9312 only has boot ROMs for floppy and paper tape. I would like to find someone who can burn me a RL02 boot PROM.
This is all like a giant puzzle, and I enjoy puzzles and am very good at solving them. It just takes time.

 

[erd]

Booting an RL11 without boot PROMs

Booting an RL11 without boot PROMs

I used to boot the RL02 by dropping some value into its CSR that caused it to DMA the first sector of the pack into the first page of memory. Because there was a perceptible amount of time between that command and the command to start executing the bootstrap, no actual code was required.

ISTR the sequence was something like...

o Reset the machine (power on or depress INIT or however)
o Set the READ and GO bits in the RL-11 CSR (deposit 14 into 174400?)
o Watch the ready light on unit 0 blink once
o Start the bootstrap (jump to/start at 000000)

I remember doing this on, at least, a machine with console ODT (as opposed to one with a front panel). Don't recall if it was Qbus or Unibus, but the only difference is the number of 1 bits at the front of the CSR. The "init" stage is important because that resets the block counter and the DMA location to 0, something you want in a boot sequence.

Same sort of thing works with an RK611/RK07, too. Just a different CSR (177400).

There's also some boot stuff at:

http://www.dunnington.u-net.com/public/ODT/SourceCode/

and

http://www.psych.usyd.edu.au/pdp-11/bootstraps.html


-ethan

 

[Peet42]

DEC discs

DEC discs

I'm a bit clueless on DEC part numbers, so bear with me, but one of my friends has a PDP11/RT11 box with two 10MB single-platter removable storage units (and about ten platters) plus three MFM drives on what looks to be a third-party controller that supports up to two MFM chains (4 drives)... It currently has a 20MB, a 60MB and an 80MB fitted, if I recall correctly, the 60MB at least being a full-height unit recycled from a 286 PC.

Although he has two platter "drawers", he only has one cable, so the lower drive isn't actually in use. If anyone's *really* desperate for one (with a few platters, of course) let me know and I'll pass the message on. Note, they weigh a ton (it takes two people to unhook the drive) and you'd have to make your own transport arrangements. He won't be looking for money for it, but a swap of any other interesting surplus DEC parts would probably be appreciated...

 

[erd]

Re: DEC discs

Re: DEC discs

I'm a bit clueless on DEC part numbers, so bear with me, but one of my friends has a PDP11/RT11 box with two 10MB single-platter removable storage units (and about ten platters)

That sounds like an RL02. They were, at one point, over $2,000 USD, but now the shipping costs more than the drives. You can put up to four on a single controller (but you need the right numbered plugs)

plus three MFM drives on what looks to be a third-party controller that supports up to two MFM chains (4 drives)... It currently has a 20MB, a 60MB and an 80MB fitted, if I recall correctly, the 60MB at least being a full-height unit recycled from a 286 PC.

That was a common arrangement for people who didn't want to pay the money DEC used to get for disks. I just got something similar to what your friend has, but it's one drive chain, and uses ESDI, not ST506/ST412 drives ("MFM"). For those that know what it is, it's an Emulex QD21. I'm now off in search of newer firmware (I have "rev D" and the instructions, but the newer firmware is easier to use).

Although he has two platter "drawers", he only has one cable, so the lower drive isn't actually in use.

The "drawer" is typically called a disk drive; the "platters" are typically just called "disks", or perhaps "packs" or "cartridges", just to throw the lingo out there.

Those cables aren't exactly common these days. Unfortunately, lots of places who throw out hardware, deinstall it with bolt cutters. I rescued some PDP-11 gear from a local factory a couple years back; I was lucky enough to get some time with the gear in its original location and disconnect *everything* for the stevedors to move it. Most rescues are not so pleasant.

If anyone's *really* desperate for one (with a few platters, of course) let me know and I'll pass the message on. Note, they weigh a ton (it takes two people to unhook the drive) and you'd have to make your own transport arrangements. He won't be looking for money for it, but a swap of any other interesting surplus DEC parts would probably be appreciated...

The most important thing to mention is where he's at - so people can predict shipping/driving costs. I have several drives (and controllers), so unless it's in town (Columbus, OH), I'll pass.

-ethan

 

[tradde]

I might be interested in the pdp-11, depending on where it is located. I still am trying to get one of my 11s working. So what's one more to add to the collection.

 

[Peet42]

Ethan - it's in Aberdeen, Scotland, so I guess you won't be interested, then... :lol: (Sorry, I assumed people would get my location from my BBS profile if they were seriously interested; just laziness on my part I guess. )

Tradde - Only the "surplus" drive is up for grabs; the rest of the machine has been promised to someone at the local Linux User Group.

 

[tradde]

Just a note. Finally got my 11/34a to be bootable from the RL02. A friend
helped me set up the TU58 emulator and I booted from it using a DL11-V
set to the CSR and vector of a normal TU58. This worked. I can now boot
the 11/34a, but I am working on the 11/84. Last night I finally found my NPG problem. I had tried changing the jumper and then found out I still
had to use G7273's in the primary backplane. Still no good. But on moving the UDA50 from slots 6,7 to 7,8 it now lets me install the terminator and still be able to run. I hope this is why it would not boot
from the image on the RL02.

Question. Is an RA80 as much of a power hog as the RA81? I would make a guess of Yes. I just got on of those. I do have an RA92 which
seems to be in good working order and will make that my boot drive if
I can boot from the RL02.
Tim Radde

 

[Allison]

As a DEC user and owner...

depending on system...

TU58, yes really, slow too!
TU58 simulator (uses RAM, ffaster)
RX02, with RXV11 and RXV21
RX50, RX33(teac FD55GFV) on RQDX3
Also use Sony 3.5" on RQDX3
RD50, rd51, rd31, rd32 on RQDX2 and RQDX3 boards.
RL02 with both RLV11 and RLV21 controllers.

I tend to experiment

Allison