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3736Re: correction - hard drive analysis

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  • Herb Johnson
    Jul 3, 2006
      --- In midatlanticretro@yahoogroups.com, "B. Degnan" <billdeg@...> wrote:
      > For the IBM XT you need to use the reference disk to format the hard
      > if it's from an alien system. I should have thought of that being
      an ex
      > IBMer...but it's been a while. In the process of formatting a drive
      > Bill
      Bill, as I remember XT's and MFM controllers, many of those
      controllers had a "low level format" routine in their BIOS ROM. That
      routine was accessed by using DEBUG and starting at a ROM address,
      something like C300:0005. A Web search on those terms should find this
      info. POWER THE DRIVE FOR SEVERAL MINUTES before doing this, so it's

      A low level format will rewrite all tracks and sectors. I recommend it
      so that any marginal tracks can be recovered. However this may also
      wipe out any info about "bad" tracks found by previous use.
      Consequently a reasonable next step is to use a program to test and
      mark bad tracks, perhaps the program you mentioned.

      The problem is that relative to drives today, the old MFM drives had
      limited self-diagnostics. Also becuase of their advanced age, they
      will be marginal and have physical errors, probably. For any serious
      use of such drives, they should be reformatted and tested THROUGHLY.

      Can you format under MS-DOS and use on DEC or other OS's? Low level
      formats are not OS dependent; they CAN be controller-dependent. High
      level format which determines drive partitioning IS OS dependent.
      Features like "bad blocks" may or may not be OS dependent. Best
      practice is to low level format and partition on the destination OS
      and controller - but testing on a more demanding controller and OS is
      a good idea!

      Other MARCH associates know more about MFM drives than me and can
      probably advise you, or more likely remind you of tricks you learned
      and forgot.

      Herb Johnson

      Herbert R. Johnson, New Jersey USA
      <a href="http://retrotechnology.com/herbs_stuff/"> web site</a>
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