CDC BR3C9 disk
                  dribve unitDate of Introduction: 1974-1975

Type: Disk drive using removable disk packs

Capacity per drive:

    8Bits per Byte

    13440 Bytes per track

    19 tracks per cylinder

    440 cyclinders per disk pack

    This results in 1031965440Bytes (98.4MBytes)

Disk pack: CDC 871, 879 or 881 ?

Rotational speed: 3600RPM

Positioning technique: Voice coil drven by servo loop

Positioning time track-to-track (average): 8.33ms

Power requirements: Standby: 500W, Accessing: 1300W

Dimensions: Height: 100cm (39.5"), Width: 56cm (22"), Depth: 112.64cmcm (44")

Weight: 300kg (660pounds)

                                                                                                     S/N: 16496


This disk drive unit was part of the remaining parts of the Computer Museum Aachen (CMA) collection. Everything that the Computer History Museum of California could not take was left in a hangar for several years until rediscovered. The Hangar was about to get torn down and a major effort was undergone within the german community of classic computer enthusiasts to save as much as possible from being scrapped. 

It is unknown to me to which Honeywell Bull computer system installation this disk drive unit belonged to. Maybe somebody  reading this is able to unveil where the Honeywell Bull installations that were donated to the CMA came from.  This disk drive seemed complete and in an acceptable shape to me which is why I decided to save it. It belongs to the BR3xx type of CDC drives that were OEM'ed to other computer vendors and customized if required. So far, I was not able to figure out what the differences of the C9 unit are compared to other BR3 disk drives. Documents can be found on bitsavers, but they do not cover BR3C9-type of drives. Unfortunately, no documents came with this unit.

The drive is waiting for restoration and comissioning. If anybody as disk packs for these drives, please get in contact with me. I'd be very interested in these.

More pictures of the CDC BR3C9 disk drive unit:

side angle
Left: The drive was covered in dust when I moved it out of the hanger with a friend.

Right: Opening the hinge and door of the bay reveals the stack of disk heads.
open disk bay
close view of disk bay
the drive was fairly clean under the cover. In any way, it will have to be cleaned and run for a complete day in a clean environment for loading a pack one day - provided that the restoration and commissioning allow to get to this point. Disk packs anybody? :)
On the back of the drive is hidden behind a door a remote service panel.
local panel
vacuum tubes
top-view-picture taken at the back of the drive. The tube is used to transport clean air that runs through filters before being flushed into the disk pack bay. 
Impressive mains power switch of the drive's power supply
main power
field update
A switch with the inscriptions "Chain I seize, Normal, Chain II seize". Does anybody know what that is good for?
On the left is visible the CDC field change order log. Humidity has left traces on the paper.
Picture of the field change order log. Three so-called field-change-orders (FCOs) where installed on 1st of Octobre 1977. Probably at the time of installation. However, this is just an assumption!

The FCOs are:

Note the very futuristic printer font!
field update
                      log: close view