16 Jan
2014
16 Jan
'14
3:08 a.m.
I pulled out my DEC RD53 for testing the archiver and surprise the heads
were stuck. I opened it and freed them but wasn't able to find the bumper
that is the cause of the problem. I put pictures here.
http://www.pdp8online.com/rd53/rd53.shtml
Does anyone on the list know where the bumper is and can say in relation
to my pictures? The first drive hasn't restuck so far but I have another to do.
Also does anyone know the data format for the stuff the RQDX3 puts on the first
few tracks? I think its the sparing information and other disk organization
information. If it wasn't too hard I was going to see if I can convert my
extracted data to an image usable under SIMH.
The low level format is strange. The first 3 sectors on track 0 are
in one format then 3 track worth of sectors with a different CRC code which
is where I suspect the controller is storing its stuff. Also some funny
stuff at the end of the disk.
16 Jan
16 Jan
3:37 a.m.
On Jan 15, 2014 7:11 PM, "David Gesswein" <djg at pdp8online.com> wrote:
Also does anyone know the data format for the stuff the RQDX3 puts on the
first
few tracks? I think its the sparing information and
other disk
organization
information. If it wasn't too hard I was going to
see if I can convert my
extracted data to an image usable under SIMH.
The low level format is strange. The first 3 sectors on track 0 are
in one format then 3 track worth of sectors with a different CRC code
which
is where I suspect the controller is storing its
stuff. Also some funny
stuff at the end of the disk.
Does this apply to the RQDX3 disk format?
Disk format for secondary storage system
US 4434487 A
https://www.google.com/patents/US4434487
3:51 a.m.
On 1/15/14 7:37 PM, Glen Slick wrote:
Does this apply to the RQDX3 disk format?
Disk format for secondary storage system
US 4434487 A
https://www.google.com/patents/US4434487
Did the RQDX3 come out of Colorado Springs?
From the dates, it looks more like something for
the RA8x/RA6x
The stuff at the end would be BAD144 data, or did
they stop using that when they switched to MSCP?
I guess Allison would know.
Didn't she just say the disk geometry was on the
first track?
9:14 p.m.
Hello,
On Thu, Jan 16, 2014 at 4:08 AM, David Gesswein <djg at pdp8online.com> wrote:
I pulled out my DEC RD53 for testing the archiver and
surprise the heads
were stuck. I opened it and freed them but wasn't able to find the bumper
that is the cause of the problem. I put pictures here.
http://www.pdp8online.com/rd53/rd53.shtml
Does anyone on the list know where the bumper is and can say in relation
to my pictures? The first drive hasn't restuck so far but I have another to do.
Note: I have only done this once.
The bumper is actually inside the head assembly (or whatever you call
it, lower left in your picture), it is kind of hard to remove it
without dissassembling the head assembly.
So I took the easy way out: while holding the head away from its
resting position I inserted a paper strip into the correct "slot" in
the head assembly and that worked. Look at the movement of the part
when the head is going to the resting position to figure out which
"slot" is the correct one. I used a paper strip that just fit into the
slot width and depth wise.
YMMV.
--
Regards,
Torfinn Ingolfsen
17 Jan
17 Jan
12:47 a.m.
On 01/16/2014 04:14 PM, Torfinn Ingolfsen wrote:
Hello,
On Thu, Jan 16, 2014 at 4:08 AM, David Gesswein <djg at pdp8online.com> wrote:
I've done it many many times. The bumper is not on the side of the magnet
stack you point to. Its around the corner on the other side and down deep.
I used to do the paper thing but decided it was inviting trouble, hasn't
happend
yet, but that drive is now over 20 years old. Now I reach in with a
forcep and pull
the thing out. It clunks loud when powered down but none have failed
I pulled out my DEC RD53 for testing the archiver
and surprise the heads
were stuck. I opened it and freed them but wasn't able to find the bumper
that is the cause of the problem. I put pictures here.
http://www.pdp8online.com/rd53/rd53.shtml
Does anyone on the list know where the bumper is and can say in relation
to my pictures? The first drive hasn't restuck so far but I have another to do.
Note: I have only done this once.
The bumper is actually inside the head assembly (or whatever you call
it, lower left in your picture), it is kind of hard to remove it
without dissassembling the head assembly.
So I took the easy way out: while holding the head away from its
resting position I inserted a paper strip into the correct "slot" in
the head assembly and that worked. Look at the movement of the part
when the head is going to the resting position to figure out which
"slot" is the correct one. I used a paper strip that just fit into the
slot width and depth wise.
YMMV. from that.
One HDA has out lasted two boards so
far!
I wrote this up maybe two decades or more ago on the comp.os.PDP11 or
maybe VMS usenet lists.
Allison
10 p.m.
On Fri, Jan 17, 2014 at 1:47 AM, allison <ajp166 at verizon.net> wrote:
On 01/16/2014 04:14 PM, Torfinn Ingolfsen wrote:
I thought the picture looked a bit different.
To be clear; the bumper is inside the metal lump where the axle for
the heads are.
Hello,
On Thu, Jan 16, 2014 at 4:08 AM, David Gesswein <djg at pdp8online.com> wrote:
I've done it many many times. The bumper is not on the side of the magnet
stack you point to. Its around the corner on the other side and down deep. I pulled out my DEC RD53 for testing the archiver
and surprise the heads
were stuck. I opened it and freed them but wasn't able to find the bumper
that is the cause of the problem. I put pictures here.
http://www.pdp8online.com/rd53/rd53.shtml
Does anyone on the list know where the bumper is and can say in relation
to my pictures? The first drive hasn't restuck so far but I have another to do.
Note: I have only done this once.
The bumper is actually inside the head assembly (or whatever you call
it, lower left in your picture), it is kind of hard to remove it
without dissassembling the head assembly.
So I took the easy way out: while holding the head away from its
resting position I inserted a paper strip into the correct "slot" in
the head assembly and that worked. Look at the movement of the part
when the head is going to the resting position to figure out which
"slot" is the correct one. I used a paper strip that just fit into the
slot width and depth wise.
YMMV. I used to do the paper thing but decided it was
inviting trouble, hasn't
happend
yet, but that drive is now over 20 years old.
Do you say the paper fix has lasted twenty years? That's great.
I wrote this up maybe two decades or more ago on the
comp.os.PDP11 or
maybe VMS usenet lists.
I actually read about the procedure on this very mailing list.
--
Regards,
Torfinn Ingolfsen
4002
days inactive
4003
days old
5 comments
5 participants
participants (5)
-
aek＠bitsavers.org -
ajp166＠verizon.net -
djg＠pdp8online.com -
glen.slick＠gmail.com -
tingox＠gmail.com