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DEC Rainbow HDD problem

O

Old Computers

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I recently acquired a DEC Rainbow computer, and it worked perfectly, including the hard drive.

Today the computer froze, and I had to turn it off (the setup screen wouldn't even show up to do a reset). I did receive error message 16 Interrupts off, and another message regarding the main board (I forget the number) when I used the reset sequence. With the second message the diagnostic lights on the back were all lit except for light 6.

Since this incident, the computer will not boot from the hard disk, and the access light does not extinguish after the system first tries to access the drive. When I run the diagnostics disk it gives me the message that the drive is not ready, I am guessing that this has to do with the access light.

I have tried the standard troubleshooting procedure of removing and reseating the cables and controller card. I did not remove any other cards from the system.
 
I have some good news and some bad news. The bad news is that the boot floppy can't access the winchester drive and it says that the drive is uninitialized, and fdisk will not run terminating with the message that the partition information cannot be found. The good news is that the drive might not be crashed. The diagnostics disk indicates that the controller may be at fault. The drive passes its checks on cylinders, motor speed and similar things, but the other tests terminate with the message drive not ready or (I can't remember the exact wording) Winchester controller status: incomplete check. I believe that if the drive had crashed then it would give other errors, and that the drive would have attempted to seek, but I do not hear the drive attempting to seek when these tests are being run. The way the diagnostics behave suggests to me that the fault is with the computer and not the drive.

Drive A has also started to produce some read errors. I had to boot the diagnostics from drive B eventually because drive A would say system load incomplete or it would just freeze with the access light illuminated (although I could still access setup to reset the computer).
 
I think you should clean the heads in the RX50. You can see from the RX50 print set how everything comes apart and you can get to the heads and sensors and everything else and give it a good cleaning.

As for the hard disk, I assume it's an RD51. Do you care what's on it? Can you put it on an RQDXn controller in an 11 to try it out there (erasing everything as a result of running a write/read exerciser.) If it works on the 11, you could rule out the RD51. If it's the controller, then we have to find the print set for that and you have to roll up your sleeves.

Depending on the vintage of the controller, I think you can put an RD31 in there. You could try a known good RD31 (or another RD51, but I assume you haven't got one) and see if it behaves properly. Then the problem would be with your RD51.

Lou
 
I do not know if the drive is an RD51. It is Segate branded, and I cannot find any markings on it to indicate its model. Since it is not parked I am a bit reluctant to remove it from the system again to search for a label in fear of crashing the drive (if it is not already crashed). I have read that the Rainbow's controller is ST-502 compatible. Could I find another controller that works in another system to check and see if the drive behaves with that controller?

As for the data, I do care about it. That drive contains the only software I have for the system (games, Lotus 123, GWBasic, WordPerfect, etc), and I do not have any of the original media for it, save the MS-DOS install disk.
 
Sure, if you are lucky enough to find another disk controller for the Rainbow, you can swap controllers. There are no settings to set. I think those controllers are sufficiently rare and desirable though that it should be repaired if found to be broken.

Yes, it is an ST-506 (RD50) interface. RD51 is actually an ST-412 drive, which is what most plus models got.

A fellow Jeff (on these forums) runs a most excellent site where backups of most of your software await you : http://rainbow-100.com/ . You can make RX50s on a PC with a 1.2MB 5-1/4" floppy drive. I loaded the hard disk in my rainbow from the goodies Jeff has on this site.

Lou
 
Thanks for pointing that site out to me. It appears that almost all of the software that is on the disk is there!

Unfortunately I do not have a controller for that drive on my PDP-11, and my PDP-11 is still on the workbench with its PSU problem. I noticed that the site you mention has a sector scanner program for DOS: http://rainbow-100.com/archives/110/
Running that while using the boot disk might help figure out something. I forgot to mention this earlier, but the seek light extinguishes when the DOS boot disk attempts to access the HDD. That might allow the sector scanner to check the drive.

I notice that the website also has CP/M. I know that the formats are different, but could I use that boot disk to try and access the HDD as well?

As for using a different controller, I was thinking more along the lines of using a Seagate controller I have in a different computer if it is compatible. The more I think about that idea though the more I realize that it probably wouldn't work for me.
 
I am fairly sure that booting CP/M will not be useful in helping you with your current problem.

As for the Seagate controller in some other computer, if you're talking about the board that's mounted on the drive (under the HDA), it would have to have come from another RD51. If you're talking about the bus interface, it would be useless. The rainbow is not at all an ISA bus machine.

At this point, you need to first narrow down if this is a problem with the drive, or the controller. It very well could be the controller in the Rainbow, and that the RD51 is fine. You may need to find someone local to you to lend you a controller for further testing (unless you are ready to get out the scope, prints, and roll up your sleeves.)

Lou
 
I think I am ready to do diagnostics myself. What page on bitsavers would I find the print set? I have looked through the DEC folder, but I see no subfolder that says Rainbow on it.
 
Unfortunately, I too have never found the print set for the Winchester disk option. I looked all over the internet, as well as through a PC-KIT fiche set I have (I think the previous owner of the set did not update it.) It is possible that Mr. RSX11M+ may have a fiche.... If it is found, I certainly want a copy also!

Lou
 
Let's hope one can be located. Until then is there anywhere that documents the signals that go to the drive? I assume that since the controller is ST-502 compatible the signals should be the same. I could look at those with my scope.
 
Is the PC100 RD51 controller the proper disk controller for the Rainbow? The picture of it looks identitical to the one I have in my computer. And I believe that the Rainbow was also referred to as the PC100.

I have also found some M8639 RDRX Disk Controller Cards for sale. Do you know if this is for Unibus or Qbus? Searching for it on the internet only produces results for companies reselling it.
 
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So why is it that the RQDX1 can control RX50 and RD51, but RUX50 only the RX50? Was this a DEC marketing strategic move to ensure that no low end disks ever got used on Unibus systems?

Lou
 
I've wondered that myself! And speaking of documentation, does anyone have any for the RUX50 (M7522)? I've searched diligently in the usual net-places and found nothing. Have one in need of repair ...
 
Paul,

I will check my fiche this evening. I know I have one fiche on the RUX50. It's either the tech manual or the print set. I think you would probably want it, whichever it is. If it is a print set, it will be a little difficult for me to scan since my fiche reader lens is for letter-size pages. I'll report back tonight.

Lou
 
I tried an experiment today. I disconnected the power from the HDD and I tried booting to the drive. I get the same error messages that I get if I were to try to boot to it with the HDD powered. The only thing I didn't try was the diagnostics. Does this help with diagnosing the problem any?
 
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