Hello: I have an old Seagate ST-238R drive. I'm the original owner and it stopped working in the early-90s when I foolishly deleted system files to make room for a football game. (I was 12 at the time). However, I still have the drive and am hoping to get the data from it as it has various writing by me and my family saved on it. I've brought to some harddrive recovery places to no avail. A friend of mine told me about retrocomputing and suggested I post here. I'm wondering if the data might be salvageable and how I might go about extracting it?

top of Seagate ST-238R bottom of Seagate ST-238R

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    If the data structures are intact, then reading with an appropriate controller/bridge should be no big issue. The ST-238 is a standard (>ST-412 interface) MFM-drive. Maybe have a look at this questions.
    – Raffzahn
    Commented Nov 10, 2019 at 18:40
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    Possible duplicate of How can a ST-412 MFM hard drive be integrated with a modern PC?
    – Raffzahn
    Commented Nov 10, 2019 at 18:41
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    In my experience sometimes you can't read a drive if it's moved to a different controller, so if you can't read it on one system, it might simply mean you need to use a different controller, a different computer, or both. Since it's a ST-238, probably you need an RLL controller, but 8-bit vs 16-bit is unknown. Start with 16-bit, a WD1006-SR or WD1006-RA will be easier to get. If all you did was delete system files, you should be able to read it simply by booting from a DOS diskette of the appropriate version. Any version of DOS 3.x or higher should do fine.
    – Ken Gober
    Commented Nov 10, 2019 at 22:56
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    @Raffzahn As far as I know the ST-xxx drives (such as ST506) can support different low-level formats just like floppy disks can: Depending on the controller connected, the floppy or ST-xxx hard disk can save MFM or RLL data... Not using the same controller that was used for writing the ST-xxx hard disk, you will have the same problem as with floppy disks: It's impossible to read a VC1541-formatted floppy on a DOS PC. Commented Nov 11, 2019 at 6:28
  • @MartinRosenau Well, isn't that always part of the process to get an old drive working again? It also doesn't change the fact that it's a duplicate.
    – Raffzahn
    Commented Nov 11, 2019 at 7:54

3 Answers 3


The ST-238R shown in the image is an RLL (Run Length Limited) drive and will not work correctly with a standard MFM controller, although it has the same ST506 electrical interface and cabling. To read back your data, you will need an RLL controller, which unfortunately are less common than MFM controllers and might not be easy to find.

RLL is an encoding method that allowed 50% more data to be stored on the same hard drive platter compared to MFM, and allowed for higher data transfer speeds. However, it needed more accurate drive mechanics. Back in the day it was even possible to connect a normal MFM drive to an RLL controller and get 50% more capacity (albeit less reliable).

  • Unless somebody formatted the drive at smaller capacity as an MFM drive. Commented Nov 11, 2019 at 19:56
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    When looking for a suitable controller, make sure it is RLL (as was said. But an MFM controller will merely not work in most cases), make VERY sure it is not ESDI (Electrically Speaking, Dangerously Incompatible!). Commented Nov 11, 2019 at 20:02
  • Thanks so much for the answer. This is tremendously helpful. I ended up finding an RLL controller that was used for an ST-238R on ebay. So I now have the drive, the controller and cables. Is the next step to find an old computer to put them in? Or are there other ways to access the drive through the controller?
    – Joego
    Commented Nov 28, 2019 at 0:53

The fact that there are two edge-connectors on the drive tells me that this drive uses the MFM or ST506/ST412 interface (or related interfaces such as RLL or ESDI). These were used on the earliest of PCs and compatibles, as well as other computer systems of the 1980s. This predates the use of SCSI and IDE (ATA) hard drive interfaces that were common from the 1990s onwards, so your options will be limited. Here are the two main options I see:

Get an old computer / interface card

If you're able to find a suitable MFM interface card, it will most likely be an ISA card, so you will need a computer that has ISA slots to connect it to. Alternatively, there were MFM to SCSI bridge boards, which could allow you to connect the drive to a SCSI card instead. (That means you could use a computer with a regular PCI slot, if you have a suitable card.) This related question has some more details on this option.

Use an emulated interface on custom hardware

Some people have developed bespoke hardware interfaces that can connect directly to the hard drive (emulating the computer) and image its contents, or connect to a computer and use such an image to emulate the hard drive. Two examples of these interfaces are the DREM hard drive emulator, and a PDP-8 oriented board. Neither of these options is particularly cheap, however.


One other thing to consider, in addition to having the correct interface, is whether the electronics are damaged in some way as to cause the drive to overheat.

I've had some success in the past pulling data from "dead" drives by putting them in a refrigerator or freezer and cooling them down to the point where it's possible to get (some) data off the drive before it overheats and stops working.

YMMV. Good luck!

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