DOS ain't dead - Volumes vs physical storage media

Volumes vs physical storage media | WAS "Protectmod handl" (Developers)

posted by bretjohn , Rio Rancho, NM, 28.08.2010, 16:35

> When copying to the same HD, you preferably use a BIG BUFFER
> (say 16 MiB), while in other cases (HD0->HD1, HD0->RAMDISK,
> HD0->USBstick0, USBstick2->USBstick2, ...) a small buffer (say 64 KiB)
> would be sufficient and maybe even faster.

Nice idea, but unfortunately won't work too well without adding another INT 13h extension. The maximum number of sectors (blocks) you can transfer to/from a disk in a single INT 13h transaction is 255, or 127.5 kiB (assuming the standard 512 bytes/sector). Also, the memory address provided for the transfer is always expected to be in segment:offset format, so that automatically limits it to 64 kiB.

You could load a "large buffer" with multiple INT 13h requests and then empty the buffer the same way, which may save a little bit of head thrashing on a real hard drive (with actual platters & heads & tracks) if the sectors were in fact contiguous.

> Also storage media durability should be reported (true for HD, sticks,
> floppy, false for RAMDISK).

I would probably use a term other than "media durability" for that concept. At least to me, HD's & CD's are more durable than flash disks (which by design have a limited lifespan and should be treated as unreliable & disposable like floppies are). To me, the concept you're trying to impart is more like "data durability" (or "permanence" or "stickiness" or something like that), not "media durability".

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Complete thread:

Protectmode handler called from realmode - Laaca, 12.08.2010, 21:12 (Developers)
- Protectmode handler called from realmode - ecm, 12.08.2010, 21:24
  - Protectmode handler called from realmode - Laaca, 13.08.2010, 01:46
    - Protectmode handler called from realmode - Japheth, 13.08.2010, 07:31
      - Protectmode handler called from realmode - bretjohn, 13.08.2010, 18:43
        EDIT: Protectmode handler called from realmode - bretjohn, 13.08.2010, 19:25
        Volumes vs physical storage media | WAS "Protectmod handl" - DOS386, 26.08.2010, 09:33
        Volumes vs physical storage media | WAS "Protectmod handl" - bretjohn, 26.08.2010, 19:03
        Volumes vs physical storage media | WAS "Protectmod handl" - DOS386, 27.08.2010, 03:25
        Volumes vs physical storage media | WAS "Protectmod handl" - bretjohn, 27.08.2010, 16:47
        Volumes vs physical storage media | WAS "Protectmod handl" - DOS386, 28.08.2010, 01:26
        Volumes vs physical storage media | WAS "Protectmod handl" - bretjohn, 28.08.2010, 16:35
        Volumes vs physical storage media | WAS "Protectmod handl" - DOS386, 06.09.2010, 20:10