24 Nov
2009
24 Nov
'09
10:37 a.m.
My expeirience is that if you have a drive with a
correctly-aligned
positioner/head assemly, you can remove it as an assembly, and put it
back in _the same drive_ and it will still be alighed. But if you move
positioenrs between drives you have to do a realignment.
In my case unfortunately that would not be the case as the best I can find
are two other units in unknown condition from a completely different set of
drives.
The alignment procedure is not hard if oyu have the
alignment pack. You
also need a 'scope (but just aout any 'scope will do) and a way of moving
the heads to a particular cylinder and selecting head 0 or head 1. I had
no prolems using a PDP11 + the appropriate controller for this, just
togging values int oteh controller registers from the PDP11's font panel.
If you use a PDP9/e, I think you have to write a trivial program for this.
I can easily get hold of a scope but a calibration pack is a different
story.
THe disk packs are different between the PDP8 and PDP11
systems. They're
hard-sectored (by notches in a metal ring on the disk hub), PDP11 packs
are 12-sectory, PDP8 packs are 16 sector. The former are _much_ easier to
find.
I think if I could find the rest of the system I might also find the packs
as well. Since this was a local and very little known recycling job only a
few businesses in town and university staff drop stuff off. I really wish I
knew dropped this off but alas, no records are kept on who drops off what.
My best bet is either the hospital or it came from someplace in the
university. Where exactly I have no idea.
24 Nov
24 Nov
11:57 a.m.
I can easily get hold of a scope but a calibration
pack is a different
story.
Maybe someone with a spare drive that could be dismantled and someone
who could create the specific hardware to write analogically the pack, could
create a machine for creating alignment packs?! :o)
It was done before with 5 1/4 disk drives... :oD
12:18 p.m.
Alexandre Souza - Listas wrote:
Maybe someone with a spare drive that could be
dismantled and someone
who could create the specific hardware to write analogically the pack,
could create a machine for creating alignment packs?! :o)
Crisis Computer in San Jose had the equipment to create them, and has them
in stock. They aren't cheap.
You could probably get something good enough by bulk erasing a platter and
writing a program to format and write a single track on an aligned drive.
It won't be as good as a cat-eye pattern, but peaking on track center may
be close enough.
On the other hand, it isn't impossible to find used red packs.
CLEAN packs may be more difficult, though.
The bigger problem is after alignment, you may no longer be able to read
the packs that you have, which may have been written on an out of alignment
drive.
4:17 p.m.
My expeirience is that if you have a drive with a
correctly-aligned
positioner/head assemly, you can remove it as an assembly, and put it
back in _the same drive_ and it will still be alighed. But if you move
positioenrs between drives you have to do a realignment.
In my case unfortunately that would not be the case as the best I can find
are two other units in unknown condition from a completely different set of
drives. I can easily get hold of a scope but a calibration
pack is a different
story.
They are not easy to find. The good news is that companies other than DEC
made compatible drives (the RK05 was y no means the first!) and that the
alignment packs for these will do for an RK05 too. I am told you can even
use the alignnment pack from a low-density dirve (RK02-compatible) if you
stick a little bit of shim in the centre hole of the hu. THe details are
in one of the DEC maintenance manuals.
-tony
5388
days inactive
5388
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3 comments
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participants (4)
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aek＠bitsavers.org -
ard＠p850ug1.demon.co.uk -
ball.of.john＠gmail.com -
pu1bzz.listas＠gmail.com