Problems reading older disk on newer drive

[Nico de Jong]

From: "Vintage Computer Festival" <vcf at siconic.com>
Subject: Problems reading older disk on newer drive


> 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.
> 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?

Normally, there would not be a problem, supposing it is a 360K disk (I guess
you are talking about 5.25" disks).
What I _have_ seen, is that "modern" BIOS'es have problems / cannot read
disks formatted as 320K. Back in the old days, 5.25" disks came in even more
flavours, like 160K (I've never seen an 80K 5.25" though)

I cant find my DOS manuals right now, but there used to be a function in
DEVICE in CONFIG.SYS where you could do some rather clever things with
regard to disk formats.

If your Octopus system had been working, you could have done a Transfer /
Input / Floppy / Analyse. This will also reveal if it is a proper MS-DOS /
PC-DOS disk, or some knock-off. There were some DOS OEM versions around
(Sord, for one), which could read and write 360K disks, but puked when
presented for 1.2M disks.

Nico