27 Oct
2024
27 Oct
'24
6:55 a.m.
Can anyone identify the 14" HDD seen in the following photo (not mine)?
It's unusual in that there are two moving heads on the top surface of the
platter. I presume that there's a fixed head on the bottom surface for the
clock track. This is from a Data General 6100 disc subsystem which is
advertised as 25MB capacity. There's a related model with half that
capacity.
https://forum.vcfed.org/index.php?attachments/img_5116-jpeg.1288418
The only thing that I can say for sure is that it's visually not a Shugart
SA4000 and that exhausts my knowledge on the subject..
While I presume that the 25-signal twisted-pair ribbon cable is for control
signals, there is also a 16(?) line grey ribbon cable connected to the left
side of the DG-specific power control PCB. I'm guessing that would be
data/clock lines from hidden electronics where the 25-signal twisted-pair
ribbon originates; not sure what else may be then happening on the
DG-specific power control PCB.
Thank you for any insights into manufacturer, model, and documentation.
-paul
27 Oct
27 Oct
8:37 a.m.
On 27/10/2024 13:55, Paul Birkel via cctalk wrote:
Can anyone identify the 14" HDD seen in the
following photo (not mine)?
It's unusual in that there are two moving heads on the top surface of the
platter. I presume that there's a fixed head on the bottom surface for the
clock track. This is from a Data General 6100 disc subsystem which is
advertised as 25MB capacity. There's a related model with half that
capacity.
It's a Fujitsu drive and has an SMD interface, but I don't know what model.
--
Pete
Pete Turnbull
10:08 a.m.
On 27/10/2024
13:55, Paul Birkel via cctalk wrote:
Can anyone identify the 14" HDD seen in the following photo (not mine)?
It's unusual in that there are two moving heads on the top surface of the
platter. I presume that there's a fixed head on the bottom surface for the
clock track. This is from a Data General 6100 disc subsystem which is
advertised as 25MB capacity. There's a related model with half that
capacity.
https://forum.vcfed.org/index.php?attachments/img_5116-jpeg.1288418
It's a Fujitsu drive and has an SMD interface, but I don't know what model.
12:35 p.m.
On 10/27/24 10:08, P Gebhardt via cctalk wrote:
I can't access the image via this link since I
don't have a login for that page,
but if it's a Fujitsu SMD drive with 14", then it can only by a M2284, M2294 or
M2298.
They didn't do more models than that with 14" platters.
And they indeed have to heads per platter side.
It's not a Fuji; the 6100 "Echo" disk is only 25MB, and all of the 14"
Fujis are an order of magnitude greater than that.
If memory serves, the 6100 was a weird combo of a 6103 or 6105 disk
(maybe from Micro Products) and a 6096 Micro Products quad density
floppy (as opposed to the 6097, which was also quad density, but
unspecified manufacturer).
--
Christian Kennedy, Ph.D.
chris(a)mainecoon.com AF6AP | DB00000692 | PG00029419
http://www.mainecoon.com PGP KeyID 108DAB97
PGP fingerprint: 4E99 10B6 7253 B048 6685 6CBC 55E1 20A3 108D AB97
"Mr. McKittrick, after careful consideration…"
11:31 a.m.
-----Original Message-----
From: Pete Turnbull via cctalk <cctalk(a)classiccmp.org>
Sent: Sunday, October 27, 2024 11:38 AM
To: cctalk(a)classiccmp.org
Cc: Pete Turnbull <pete(a)dunnington.plus.com>
Subject: [cctalk] Re: Identify 14" HDD with two heads on single arm
On 27/10/2024 13:55, Paul Birkel via cctalk wrote:
According to https://www.bitsavers.org/pdf/fujitsu/disk/FujitsuDriveList.txt as Pierre
notes it would then have to be one of these three:
M2284N 160MB 14" SMD
M2294N 330MB 14" SMD
M2298N 498MB 14" SMD
All are multi-platter drives, and all with way too _much_ capacity; the one on the photo
is only 25MB. It looks like a single-platter drive to me, and it doesn't much look
like the diagrams in B03P-4580-0100A_M228x_Apr81.pdf, even after ignoring the
multi-platter aspect. So I don't think that it's a Fujitsu.
It seems to me that it must be another manufacturer.
The VCF thread containing the image and context is here:
https://forum.vcfed.org/index.php?threads/nova-4-x-restoration.1250317/#pos…
-----
Can anyone identify the 14" HDD seen in the
following photo (not mine)?
It's unusual in that there are two moving heads on the top surface of
the platter. I presume that there's a fixed head on the bottom
surface for the clock track. This is from a Data General 6100 disc
subsystem which is advertised as 25MB capacity. There's a related
model with half that capacity.
It's a Fujitsu drive and has an SMD interface, but I don't know what model.
--
Pete
Pete Turnbull 
4:01 p.m.
In 1979 Data General started manufacturing its own two line of 14"
Winchester disk drives - a 12.5 MB [Model 6099] and a 25.5 MB [Model
6103] version. A "quad-density" 1.2 MB 8" floppy diskette drive or two
were often part of the system for installation and backup purposes.
There is usually an ID plate on the back of the disk drive that contains
the model number and DG Product number (i.e. 005-xxxxx-yy) of that
specific unit.
Bruce Ray
Wild Hare Computer Systems, Inc.
Denver, Colorado USA
bkr(a)WildHareComputers.com
...preserving the Data General legacy: www.NovasAreForever.org
Bruce Ray
Wild Hare Computer Systems, Inc.
Denver, Colorado USA
bkr(a)WildHareComputers.com
...preserving the Data General legacy: www.NovasAreForever.org
On 10/27/2024 7:55 AM, Paul Birkel via cctalk wrote:
Can anyone identify the 14" HDD seen in the
following photo (not mine)?
It's unusual in that there are two moving heads on the top surface of the
platter. I presume that there's a fixed head on the bottom surface for the
clock track. This is from a Data General 6100 disc subsystem which is
advertised as 25MB capacity. There's a related model with half that
capacity.
https://forum.vcfed.org/index.php?attachments/img_5116-jpeg.1288418
The only thing that I can say for sure is that it's visually not a Shugart
SA4000 and that exhausts my knowledge on the subject..
While I presume that the 25-signal twisted-pair ribbon cable is for control
signals, there is also a 16(?) line grey ribbon cable connected to the left
side of the DG-specific power control PCB. I'm guessing that would be
data/clock lines from hidden electronics where the 25-signal twisted-pair
ribbon originates; not sure what else may be then happening on the
DG-specific power control PCB.
Thank you for any insights into manufacturer, model, and documentation.
-paul
28 Oct
28 Oct
1:02 a.m.
Thanks Bruce. Data General actually went into the 14" drive manufacturing business,
platters, heads, positioner, spindle, and all? I've been assuming that they sourced
the drive assembly OEM and then built their finished product around that.
Yes, the associated 8" FDD is DSDD so "quad"; manufacturer is Qume (842?)
in that particular system. I imagine that DG might have used others. Christian Kennedy
mentioned MPI as the FDD manufacturer (9404B?), and possibly for the HDD, so I rooted
around in the CDC documentation on Bitsavers (thanks Al!) and I see that the 9730 MMD used
a dual head per surface configuration and from
https://bitsavers.org/pdf/cdc/discs/CDC_Drive_Models.txt this:
Model Media 1st Ship Unformatted Size Name
9730-12 14" 5/77 12.9 Fixed
9730-24 14" 5/77 25.8 Fixed
That all looks promising, however the technical details don't match very well unless
the unit in the photo is actually 12.5MB capacity [Model 6099] in which case the 9730-12
matches well with one platter, one servo head (lower surface), and two recording heads
(upper surface). The 9730-24 stacks two platters and doubles the number of recording
heads (the upper platter has the pair of heads on the underside). See:
https://bitsavers.org/pdf/cdc/discs/brochures/CDC_9730_MMD_Brochure_Oct76.p…
https://bitsavers.org/pdf/cdc/discs/mmd/64709700r8_MMD_9730-xx_ProdSpec_Mar…
https://bitsavers.org/pdf/cdc/discs/brochures/CDC_9730_MMD_Brochure_May79.p…
The CDC / MPI finished product uses a SMD interface and stacks the drive electronics over
the drive assembly. It seems reasonable to conclude that DG acquired the drive assembly
from MPI and then did their own electronics to a proprietary non-SMD interface, which
would explain the cabling visible in the photo.
The earlier product brochure is October 1976 (and is light on details), MPI ships the
9730-12 (finished product) in May 1977, the family engineering spec (rev 8) is March 1978,
the second product brochure is May 1979, and the DG drive assembly in the photo seems to
be mid-1981 based on the bad block sticker. Not sure how much earlier DG introduced the
Model 6099 but this seems like a reasonably consistent timeline.
The clear head photos in the second product brochure aren't an exact match, but they
are close. Perhaps MPI made some engineering tweaks over the lifespan in the drive
assembly?
Bruce, are you sure that DG didn't OEM the drive assembly from elsewhere, and in
particular MPI?
-----Original Message-----
From: Bruce Ray via cctalk <cctalk(a)classiccmp.org>
Sent: Sunday, October 27, 2024 7:02 PM
To: Paul Birkel via cctalk <cctalk(a)classiccmp.org>
Cc: Bruce Ray <Bruce(a)Wild-Hare.com>
Subject: [cctalk] Re: Identify 14" HDD with two heads on single arm
In 1979 Data General started manufacturing its own two line of 14"
Winchester disk drives - a 12.5 MB [Model 6099] and a 25.5 MB [Model
6103] version. A "quad-density" 1.2 MB 8" floppy diskette drive or two
were often part of the system for installation and backup purposes.
There is usually an ID plate on the back of the disk drive that contains
the model number and DG Product number (i.e. 005-xxxxx-yy) of that specific unit.
Bruce Ray
Wild Hare Computer Systems, Inc.
Denver, Colorado USA
bkr(a)WildHareComputers.com
...preserving the Data General legacy: www.NovasAreForever.org
57
days inactive
58
days old
6 comments
5 participants
participants (5)
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Bruce Ray -
Christian Kennedy -
P Gebhardt -
pbirkel＠gmail.com -
Pete Turnbull