On Sun, 19 Dec 2004, Bill Girnius wrote:
> Is it possible it's an 8 sector disk before dos 2.25?
Well sellam's mail said "PC" so I assumed IBM feces type
computer. But yes, there were many MSDOS diskette formats before
IBM, and even before MSDOS, when it was 86DOS; I think it had
the same FAT structure, I just don't recall.
>From the start however Microsoft (in one of their good ideas,
presumably after the debacle of CP/M diskette formats) STRONGLY
SUGGESTED the use of a table of diskette formats ID's with a
particular value of FATid byte. Unsurprisingly the formats were
more or less all you could cram on a soft-sectored diskette. Both
8" and 5.25" were given.
For some reason, I don't recall and may never have known, FATids
run from 0f8h - 0feh. That's not many. So there were overlaps,
but the intent (...) was FATid of FE (8" 26 sector I think)
could be re-used on a (say) 3" floppy with no confusion.
But then PCDOS did that irritating
check-for-data-in-the-boot-sector thing.
The unix M tools should be able to read any properly formatted
diskette, even if a wondows machine wont.
> ----- Original Message ----- From: "Vintage Computer Festival"
> <vcf_at_siconic.com>
> To: "Classic Computers Mailing List" <cctalk_at_classiccmp.org>
> Sent: Saturday, December 18, 2004 12:25 PM
> Subject: Problems reading older disk on newer drive
>
>
> >
> > I think we've discussed this before. Sorry if we're re-treading old
> > ground.
> >
> > I'm trying to read a disk an old double-density PC formatted disk on a
> > high-density drive. I can read the directory and certain small files
> > just
> > fine, but any files that are larger than a few sectors (or perhaps that
> > span a track) return "Sector Not Found" errors. What is the deal with
> > that?
> >
> > This is under DOS 6.22. Is there a way to get DOS to recognize that this
> > is a double-density disk and to perform whatever internal magic is
> > necessary to read the disk properly? Or is this an issue of hardware?
> >
> > --
> >
> > Sellam Ismail Vintage Computer
> > Festival
> > ------------------------------------------------------------------------------
> > International Man of Intrigue and Danger http://www.vintage.org
> >
> > [ Old computing resources for business || Buy/Sell/Trade Vintage mputers
> > ]
> > [ and academia at www.VintageTech.com || at
> > http://marketplace.vintage.org ]
> >
>
Received on Sun Dec 19 2004 - 12:51:14 GMT