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Thread: PARKAL utility output info - confused about the head

  1. #1

    Default PARKAL utility output info - confused about the head

    So today I was trying some park utilities on two of my laptops, one has MS-DOS 3.31 installed on a 20MB partition, and the other one has MS-DOS 6.22 installed on a 1GB partition. I tried PARK.COM, HDPARK.COM, and PARKAL.COM. For on both machines, after it was invoked and the heads were parked, I saw a message saying "1st Fixed disk: parked at cylinder 991, head 127, sector 63" for one (20MB partition) and "1st Fixed disk: parked at cylinder 1021, head 239, sector 63" for the other (1GB partition).

    I can understand the cylinder and sector - the heads were parked at the second-last cylinder (verified by fdisk) and the sector was always 63. However, what does "head 127" and "head 239" mean here? I know both of the laptop HDDs have multiple heads (my understanding is that the # of heads = 2 x # of platters, correct me if I'm wrong) but they certainly do not have as many as 127 or 239 heads. Does it refer to something else?

  2. #2
    Join Date
    May 2009
    Blog Entries


    You would have to disassemble it to be sure. I just tried but it crashed the disassembler I was planning on using. I expect that you have hit some form of overflow condition.

    All the drive heads should have landed in the same cylinder and sector. Normal PC drives move the entire stack of heads in unison so having a head value makes no sense.

    Using a 1985 utility on a 1 GB drive seems unwise.

  3. #3


    That's also what confused. I think it should eliminate "head" value completely. btw, I tried it on two laptops, one of them actually has a 20MB partition.

  4. #4
    Join Date
    Jan 2007
    Pacific Northwest, USA
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    As hard disks pushed the 1024 BIOS cylinder limit, they resorted to what's known as "translation mode", where the geometry is recalculated in terms of what a pre-ATA6 BIOS can accept. For example, suppose for the sake of argument, you had a disk whose native geometry was 17 sectors, 2 heads and 2048 cylinders. You could "translate" that to 17 sectors, 4 heads and 1024 cylinders.

    In fact, IDE drives of any capacity do a lot of faking geometry. For example, to get optimum use of the available platter space, you'd put more sectors on the outer cylinders than on the inner (think in terms of how running track starts are staggered so that everyone runs the same distance). (63 sectors per track is simply the maximum allowed by the BIOS).

    So, the park utility is doing its best at parking somewhere around the last available sector on the drive.

    But in fact, parking a 1GB IDE drive will accomplish little--almost all IDE drives are self-parking.

  5. #5


    Any 1 GB hard drive is going to be new enough that it is auto-parking, therefore using a head parking utility is superfluous.

    Many laptop hard drives from the '90s and early 2000s also automatically park the heads a few seconds after any drive activity, just in case you move the laptop around while it's turned on. Newer ones use a G-sensor to automatically park the heads the instant that any movement is detected.


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