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Thread: IBM 3330 Disk Pack?

  1. #1

    Default IBM 3330 Disk Pack?

    Is anyone here able to identify the correct drive for this disk pack?

    IBM Disk Drive - Southern Pacific.jpg

    I'm told that it is for an IBM 3330-compatible drive, but I would appreciate any opinions here on the matter.


  2. #2


    The below comments are from the guy I'm working with on this project:

    They called it 2314B internally.

    Yeah, though taking the dust cover off like that's a big No-no...
    Nobody wants to hear the sound they make when the heads hit a platter spinning at 3600rpm and dig a trench before the drive can stop spinning... or the actuator is torn out and the head assembly goes bouncing around inside the drive throwing sparks and other awful noises.

    It only came in 2 drive stacks - $80K in 1980. I had to write a justification for buying 1 stack for the car-hire system...

  3. #3


    Your picture is of an "official" IBM model 3336 disk pack, this one being manufactured and sold by IBM. This style pack was used on the IBM 3330 disk drive and many, many other non-IBM drives. When used on the IBM 3330 disk drive, it stored either 100MB or 200MB per pack, depending upon the 3330 drive model.

    Here is the official IBM product page:

    The Wikipedia entry:

    What is so interesting about this pack was the dominance that it obtained, outside of IBM systems, in the late 1970s and all throughout the 1980s. Some examples of disk drives utilizing this style pack were the CDC models BJ4M1, BJ4M2, BJ402, BR3D4, BR3C2, BR6xx and BR7xx (975x, 9764, 9766) which were OEM'd for dozens of other computer manufacturers such as Digital Equipment Corporation and Honeywell. Another example is the Memorex RP05 and RP06 which was widely used by DEC. Some companies designed and made their own, non-OEM'd, disk drives of this type, such as Fujitsu for their FACOM line.

    Some of these non-IBM drives were highly proprietary and some were SMD drives. The maximum capacity of a non-IBM drive using this style pack was 300MB, such as the CDC 9766 drive.

    These style packs were also branded and sold by CDC, Memorex, DEC, BASF, Dysan, and several others. I suspect that there were only a few actual manufacturers, and most of these packs on the market were rebranded (OEM'd). has an extensive collection of CDC disk drive technical manuals. It is fascinating reading.

    These packs were not always interchangeable, as I have found out. The disk drives' spindle pack-locking mechanisms and pack center locking pin designs differed very slightly, preventing disk packs of different capacities from being accidentally mounted on the wrong drive. I also suspect that the differing locking details were to limit a customer to a particular disk pack brand or brands. For example, for the DEC RP06 disk drive, it would only accept the DEC-branded RP06P 200MB pack (or a limited number of equivalents). The drive could have been designed to use any generic 200MB 3330-type pack.

    I hope this fully explains your question.
    Last edited by MossyRock; September 2nd, 2017 at 05:19 PM. Reason: clarifications

  4. #4


    Thank you, MossyRock, this is absolutely the informaiton and confirmation that I was hoping for. Very helpful and appreciated!


  5. #5


    Even though it is not quite in the range of models that MossyRock mentions as being compatible with this disk pack, I just acquired this:

    It was the right price for me to begin experimenting and testing with, to get familiar with this vintage of hard drive technology, and learn how to hack it effectively.

    I welcome anyone's comments.

    Thanks again!

  6. #6



    What you have here is rack-mount version of a CDC 9427H Hawk drive. It uses the IBM 5440 type top-loading disk cartridge and compatibles, with a 5MB capacity per cartridge. It also has a 5MB fixed disk platter, for a total online capacity of 10MB.

    I'm not sure how identical a 9425 is to a 9427H, but I would assume it is pretty close. Bitsavers has this information on the 9427H:

    We had a CDC 9427H drive in use with an Alpha Micro system back in the 1980s and it proved to be a very reliable and rugged drive.

    My concerns for a drive of this age are the condition of the heads, fixed disk surface, spindle assembly, drive belt, motor and absolute filter. Inspect the heads carefully with a dental mirror for indications of a head crash. If any are crashed, they must be replaced. If the heads are good, you must clean them before use. You will also need to inspect both sides of the fixed disk platter for damage and clean both surfaces correctly. Use CDC recommended procedures for inspection and cleaning operations for the heads and platter. Spindle assemblies have internal lubrication that dries out so it must be tested that it spins freely without resistance. Replace deteriorated belts. I would replace the absolute filter. If the absolute filter has deteriorated, which is almost certainly the case, you will blow debris onto the surface of the disk patters and likely cause a head crash.

    Before mounting and using any cartridge, you must also open and inspect it for surface damage. You must clean the both sides of the platter as well.

    I have a contact in Van Nuys, CA, that has a large collection of CDC replacement parts including those for the CDC Hawk. Some of his parts are in good condition while others are not, so if replacement parts are needed you would most likely need to travel to Van Nuys to inspect and select the parts yourself. Let me know if you need his contact information.

    I am uncertain as to how you would interface this to any modern computer although you would most likely have to design and build your own interface. However, the Hawk was such a common drive you will probably find some information on the Internet about those who have done it.

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