WTB: HP 9133/9134/9135A, HDD, also non-working

[Michael Fehlhammer]

I received an HP 9135A hard drive / floppy drive combo, but unfortunately the HDD is dead. It is a Seagate ST 506 (5 MB).
I would like to buy such a HDD as a replacement part, or a complete HP 9133/34/35A, even if it is non-working.

[Paul Berger (Canada)]

If you are not concerned about keeping it all original any MFM drive with a ST-506 interface that has at least as many heads tracks and sectors per track will probably work. When I last had a working 9135H (20MB) it had a 40MB Miniscribe drive in it and worked perfectly but of course only 20MB of the capacity was available.

[Michael Fehlhammer]

That sounds interesting. But I already tried out a ST 412 (10 MB) which is working in a 9134B. I thought it to be the closest sister of the 506. But I only received "ERROR DISC" when I tried to INITIALIZE it in my 9135A.
Maybe the controller in the oldest drives (9135A) are less flexible as the controllers in the more modern 9133 D/H/L drives?

[Paul Berger (Canada)]

The ST-506 was a standard interface throughout its life time and is really only an expanded diskette interface using step and direction signal to position the head and binary signal lines to select the head and the drive providing an index pulse to tell the controller where a track starts. The only way the controller can be sure of where it is on the disk is by reading the sector ID that is written when the drive is low level formatted.

The 10MB ST-412 was also used in the 9134B and I would be surprised if there was much difference between the A and B version other than maybe a jumper or two on the controller card. (134 is just a 9135 without the diskette drive.

[Michael Fehlhammer]

Thank you Paul for your help!
Since it seems to become a longer thread and it's somewhat off topic here, I open a new topic on VintHPCom (groups.io) and invite you and everybody else who is interested in these oldest hard disk drives to add your comments there.

[Dave Frederickson]

Hi Michael,

When I bought my 9133D off eBay I also bought a cheap MFM ISA controller. I plugged this and the HD from the 9133 into my vintage PC and ran a utility called SpinRite.

SpinRite reads each track, re-low-level formats the track, and re-writes the data. There are options to write/read test patterns before re-writing the data. In short, it tests the c**p out of the drive and realigns the data.

I also noticed that the drive was 20MB so I reconfigured the controller for a 9133H.

Dave

[Michael Fehlhammer]

Hi Dave,

thanks for the hint! I will get that utility, it sounds as if it could reanimate almost dead hdds in some cases.
Interesting that HP equipped the 9133D with a better drive than necessary.
Maybe they thought that part of the upper 5 MB (the difference between the "D" and the "H") was faulty or at least less reliable in that case?
Or they just got a bunch of ST 225 (?) cheaper than the smaller drives ...

[Dave Frederickson]

(06-06-2020 05:21 PM)Michael Fehlhammer Wrote:  I will get that utility, it sounds as if it could reanimate almost dead hdds in some cases.

Here's a video about SpinRite.
https://media.grc.com/video/wid.mp4

And here's the results of a search.
http://drummerdonnie.com/Archive/UTILITIES/SpinRite/

[Michael Fehlhammer]

The video about Spinrite sounds convincing, but some people called it "snake oil":
Spinrite criticism
In the commentary posts, on the other hand, several people report about successful data recoveries.
I can't connect to "drummerdonnie" (receive a time-out error).

[Massimo Gnerucci]

(06-07-2020 10:24 AM)Michael Fehlhammer Wrote:  The video about Spinrite sounds convincing, but some people called it "snake oil":
Spinrite criticism
In the commentary posts, on the other hand, several people report about successful data recoveries.
I can't connect to "drummerdonnie" (receive a time-out error).

FWIW I successfully (albeit slowly) recovered 3/4 HDDs with Spinrite, back in the day.
It did what it promised, when I had this as the only choice to recover lost data.

[rprosperi]

I too have successfully used SpinRite to salvage data from failing hard drives, more than once. It cannot save every situation as some sectors can be damaged beyond recovery, but this tool is truly excellent and worth every penny of its low price.

In the case of vintage drives, alignment between heads and written sectors may have drifted slightly over the years, and using SpinRite 'realigns' this by safely reading and re-writing every disk sector, so it's really the ideal tool when re-purposing old drives.