DOS ain't dead - Volumes vs physical storage media

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

posted by DOS386, 27.08.2010, 03:25

> At least in theory, this is not something you're supposed to care about

Disagree, see below about copying.

> A DOS-accessible volume doesn't have to be associated with an INT
> 13h physical device or CHS/LBA addressing at all

Right, but this doesn't invalidate the need for a such call at all (the returned info may say something else than "physical hard disk" blah blah).

> That's why things are designed the way they are, and why you're supposed to
> only use OS calls to access data inside volumes. "Going behind the OS's
> back" and directly accessing data inside a volume is not a good idea, and
> why DOS (and Windows) don't provide a way to go back and forth

Good, but see below.

> First of all, what do you mean by "high memory": UMB, HMA, EMS, XMS, or
> something else?

I meant small buffer vs big buffer. (BTW, I deprecate all memories except physical and maybe XMS, heh ...)

> It doesn't really matter whether the volumes are on the same
> physical disk or not, or even if they are on a physical disk at all.

It does matter very much, as copying to same physical disk with small buffer is very slow and exhausts the drive's durability.

> they probably never will have such calls, for security and data safety reasons

Missed the point, see above. That's why in file managers:

- There is only 1 strategy
- The user must pick the strategy
- The user must reveal what volume is on what physical disk
- Some "file managers" don't do the copying at all, they instead instruct the EXPLOITER to to the work for them :-(

> That will be fixed in the next release of USBDRIVE. I've discovered that
> this is actually a "bug" in the way some BIOS's work, not a "bug" in
> USBDRIVE as such.

Good :-)

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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
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      - 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