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How to reformat DEC RL02 diskpacks?

You should accumulate all the manuals for the RL02 and the relevant controllers for the 11 or 8. When you read the manuals, you will see that the RL packs are factory formatted. They do not get formatted in the field.

Lou
 
Lou - N2MIY said:
You should accumulate all the manuals for the RL02 and the relevant controllers for the 11 or 8. When you read the manuals, you will see that the RL packs are factory formatted. They do not get formatted in the field.

Lou
Click to expand...

the factory format was not ment to last this long and has decayed!
 
it still could be useful to be able to reformat the disk packs, I will have to see how well my ones work!
 
The factory format on my RL02 packs are fine. It is not even possible to field format an RL pack in an RL drive. The heads know where to be by embedded servo information before the sector header. The packs must have been factory formatted on a special master drive that used a very high accuracy head positioner (maybe something like a velmex unislide positoner?) that also wrote the servo information and sector headers.

RK05 is a different story and is formatted in the drive. Of course, the drive is mechanically aligned to a CE pack.

Lou
 
I'm not sure we're talking about the same thing here, as RL packs may be different than anything you've encountered before.

First, the only entity who would be capable of putting the "format" on a brand new surface would be a pack manufacturer. If this is really what you want / need, the only way would be to contact one and make arrangements. To my knowledge, no one has ever offered one for sale commercially. Back in the day, manufacturers who wanted to sell non-DEC made media had to literally reverse engineer the patterns, and create their own.

Most users didn't trust anything but original DEC media, so there wasn't much of a market. Whenever DEC sensed a threat, they just dropped their prices.

Standard RL drives do not have the capability to write the servo data, so the only thing they can do is "Re-format" one, or re-initialize it. (depending on the jargon of the operating system used)

In DECeze:

  • "Re-Formatting" implies rewriting the Bad-Sector information, which is optional under RSX. My recollection may be confused with an option to wipe out the Manufacturer's Bad Sector information that may have been for RM03 packs. At this point, I'd have to look it up to be certain.
  • "Re-initializing" is synonymous to writing a new FAT today. (AKA - INI-ing.)

rorypoole said:
the factory format was not ment to last this long and has decayed!
Click to expand...
So, I'm curious where this impression comes from? The only way I've seen packs become unusable is physical damage (incorrect removal from a drive, corrosion, contamination, head crashes, overheating and scorching, brush wear) and electronic disruption of the servo patterns. (in my case done by an emergency head retract during a write cycle - the only instance I know of)

I recall back in the day many of us were perturbed by the idea that we couldn't perform this with many of DEC's media, and sought solutions in rebellion. Believe me, nowadays this feeling is long gone. I am unaware of a pack having lost it's format due to age. I should mention that I am aware of an instance where an extremely large electromagnetic pulse demagnetized all the media in a research facility - rendering them useless. Not a natural occurrence.
 
how does an RL02 pack get damaged by overheating and scorching? the drive catch fire! lol
when I was a boy I got some used old dodgy mfm hard drives, and some where unusable and full of bad sectors, and lost data all the time, and you had to repartition and reformat the drive a lot, and it was best to let it worm up for 20m before doing anything, I found an old program on 5.25 disk and it let me low level format the drives, I then repartitioned them and high level formatted with FAT 12, after they worked like a dream, faster too as I corrected the interleave.
IDE and probably newer hard drive still have the low level format, and it is normally only done in at manufacturers, so I was thinking the DEC RL02 pack would be the same?
I have not done a low level format since I was 15 or so, but the survo tracks are probably the low level format?
 
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rorypoole said:
how does an RL02 pack get damaged by overheating and scorching? the drive catch fire! lol
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We had the same reaction. But after seeing the effect of a malfunctioning brush [built into older drives - later omitted] on a platter surface, we were believers. The pack failed a routine PM. The actual platter was hanging on a cubicle wall in my area for years. [adorned with appropriate graffiti]

rorypoole said:
...when I was a boy I got some used old dodgy mfm hard drives, and some where unusable and full of bad sectors, and lost data all the time, and you had to repartition and reformat the drive a lot, and it was best to let it worm up for 20m before doing anything, I found an old program on 5.25 disk and it let me low level format the drives, after they worked like a dream, faster too as I corrected the interleave.
Click to expand...
I too remember those days... from the PC era. These experiences are not a part of RL lore.

rorypoole said:
...IDE and probably newer hard drive still have the low level format, and it is normally only done in at manufacturers, so I was thinking the DEC RL02 pack would be the same?
Click to expand...
Unfortunately not. The drive does not physically posses the equipment to write the servo patterns, only to read them and to write between. (hopefully) The idea for this was put forth in a DEC paper as being able to eliminate tedious alignment errors and expense of previous designs by having the head dynamically aligned to the center of a track by reading the pattern from the disk.

In a removable pack system, this is ideal. However, once technology advanced to the "Sealed Winchester" drives, where the platters were not removable and tolerances much tighter - the need to low-level format arose. Mind you, it's not a bad trade-off.
 
RSX11M+ said:
We had the same reaction. But after seeing the effect of a malfunctioning brush [built into older drives - later omitted] on a platter surface, we were believers. The pack failed a routine PM. The actual platter was hanging on a cubicle wall in my area for years. [adorned with appropriate graffiti]

I too remember those days... from the PC era. These experiences are not a part of RL lore.
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can you explain about the malfunctioning brush? and routine PM?

It is good to know that the RL02 packs where build to last! but evenly the servo patterns will need to be rewritten! if you hooked up an oscilloscope to the head and measured the differences in in amplitude of the servo pattern and user data, and compered it to the min amplitude the RL02 drive can reliable use you could calculate the probable year that pack will start to die!
 
The servo burst looked just like the service manual on my 30 year old (at the time, drive and pack) RL01 :

http://www.vintage-computer.com/vcforum/album.php?albumid=63&attachmentid=4371

(after I did the head alignment after replacing a bad head.)

Lou

PS. After having spent a lot of time inside these RL drives (for a hobbyist, not a field service engineer) they look extremely well made and well thought through. I am not surprised that they are as reliable as they are. They are much more substantial than the RK05s I have.
 
I am glad I went for the RL drives, even with the large interface problems with using them with a straight 8!
any one close to me with a dead RL drive, I only need one with working moter and air system, to build a diskpack distortion tester? so it could be striped down drive parts drive
 
rorypoole said:
can you explain about the malfunctioning brush? and routine PM?
Click to expand...

It was just before my time with RLs, but apparently the original design of the disk drives included a cleaning brush in the internal mechanism. This was to sweep the surface of the platter, presumably prior to allowing the head onto it.

This brush caused such horrible issues, that it was removed from every operational drive I ever encountered [presumably a DEC FCO exists on it] In our organization, one had been missed. It was this drive that was responsible for "burning" the platter's surface, eventually rendering it unreadable. The pack had been mounted and loaded in the drive for a number of months from what we could tell. Loss of it's contents caused quite a shakeup. Management mandated that all packs in the facility be immediately cleaned and PM'd and that all RL drives and packs be returned to "DEC service contract" from then on or be physically removed from the premises.

Subsequently, additional precautions occurred when DEC instituted the "Shockwatch" program.

Please note that RL01 and RL02 drives are nearly identical, except for a few parts. The last revision of RL02 drive was capable of read-only access of RL01 packs. Pack cleaning procedures and equipment would work with both types.

rorypoole said:
It is good to know that the RL02 packs where build to last! but evenly the servo patterns will need to be rewritten! if you hooked up an oscilloscope to the head and measured the differences in in amplitude of the servo pattern and user data, and compered it to the min amplitude the RL02 drive can reliable use you could calculate the probable year that pack will start to die!
Click to expand...
For a pack in continuous use, this might be measured in 10's of decades. (a number already demonstrated and exceed by history) In storage, I would not be surprised at a much larger figure.

However, your remarks on the magnetic flux degradation are interesting, I've never heard of a theoretical analysis being performed. If there were to be a lottery on the maximum age, I'd pick a cool million years.

rorypoole said:
...any one close to me with a dead RL drive, I only need one with working moter and air system, to build a diskpack distortion tester? so it could be striped down drive parts drive
Click to expand...

I tried to raise consciousness on this subject of RL pack maintenance once before. (not much participation) I also entertained some other amusing thoughts on a related topic.

I have not found any documentation of these devices... yet. There are tolerance numbers amongst the available documentation which would allow testing of cartridges.
 
I plan to treat my RL drives and other DEC equipment well, I want them to work for a long time and spares are getting harder to find and more expensive! someone must have done some tests on the RL drive to test the servo strength? and I dont want to stick a disk pack in my RL drive before I know its good and wont damage each other, when I do have my RL drives working I will have to test the servo track and try to work out how much life is in it!
 
Rory,

I really don't think you need a disk pack distortion rig unless you have packs where it is obvious that the shockwatch is tripped. I don't have many packs myself, but if the shockwatch was tripped, I would certainly not even bother to try it.

Lou
 
so far I have 1 RL drive and diskpack both with an unknown past! the RL02 drive has a sticker with 1990 as the last time the filter was chaneged!
It was RSX11M+ post I read a while a go, and was thinking of the diskpack test rig. also postage is brutal of hardware, so any diskpacks I have to have shipped could do with being tested.
 
Lou - N2MIY said:
Rory,

I really don't think you need a disk pack distortion rig unless you have packs where it is obvious that the shockwatch is tripped. I don't have many packs myself, but if the shockwatch was tripped, I would certainly not even bother to try it.

Lou
Click to expand...

If the pack has a shockwatch on it, I would agree with Lou. In your case, with a pack actually being in the drive during transport - it would count for the condition of both.


  • Was the pack easily removed from the drive?
  • Was there any indication that the heads were on the platter while the drive was unpowered?

If the heads were in the retracted and locked position, and there is an untriggered shockwatch - the only thing I'd look for is contamination and corrosion. A flashlight examination of the platter should be sufficient for this.

However, it would be a very good idea to check out the drive on another system, rather than try to debug your PDP-8 and a suspect RL drive at the same time. Is there any indication what system the RL was last in service on?

Lou, were RL02 disks ever used on PDP-8 systems in the day? Wouldn't they have been RL01? I am pretty sure the bus controller would be compatible, but software is another matter.

Incidentally, I am unaware of any RL02 that ever had a brush. I think the brush was eliminated before introduction of the RL02.
 
RSX11M+ said:
I tried to raise consciousness on this subject of RL pack maintenance once before. (not much participation) I also entertained some other amusing thoughts on a related topic.
Click to expand...

RetroHacker_ and I disassembled a small pile of RL01/RL02 cartridges for inspection and cleaning a few months back. I haven't written up the exercise, but following various DEC guides and processes outlined online, we were able to clean up and inspect all of our packs, preventing the mounting of at least one hard crashed pack (it had "Saturn rings") that was both very clean on the outside and had a non-tripped ShockWatch stuck to it. We didn't have access to a clean room, but Kimwipes, lint-free swabs, 99% isopropyl alcohol, a bright LED flashlight and RetroHacker_'s kitchen resulted in no damaged packs.
 
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