Mail Archives: opendos/2000/11/03/13:15:55
----- Original Message -----
From: "Ben A L Jemmett" <ben DOT jemmett AT ukonline DOT co DOT uk>
To: <opendos AT delorie DOT com>
Sent: Thursday, November 02, 2000 10:17 AM
Subject: Re: DRDOS FDISK
> (The two entries for F9 are verbatim). This coding appears to be the same
> used in the BPB. (I just pulled the first sector of a FAT from a Zip disk
> and the ID there matches the BPB ID).
I also checked some diskettes and they had 29h reguardless of what was in
the first byte of the FAT.
>
> I think a fixed disk is F8h - I've checked this both on the actual HDD in
> this system and on a random Zip disk (the latter has a BPB as follows:)
Yes F8h is used for fixed disks.
> 16AB:0100 00 02 04 01 00
> .....
> 16AB:0110 02 00 02 00 00 F8 BC 00-20 00 40 00 00 00 00 00 ........
> .@.....
> 16AB:0120 00 F0 02 00 00 00 29 42-2F E6 1A 52 41 4C 31 20
......)B/..RAL1
^^
There is the goold ole 29h----------|
> 16AB:0130 20 20 20 20 20 20 46 41-54 31 36 20 20 20 FAT16
> (This is a copy and paste from DEBUG, using the commandsL 100 3 0 1 and D
> 10B L 33)
> I think Win98 (FAT32) uses a different BPB format - the media descriptor
is
> in the right place, but after that I think the values are laid out
> differently to encode the 32-bit locations.
It probably does. I did look at FAT 32 with the Norton's Disk editor in
maintenance mode, but did not really look that closely at it.
> > [Copy protection]
> > Some even used tracks beyond 39 and DOS would not copy those. AFAIK
there
> > were never any HD disk copy protection, it was only used on DD disks.
> Hmm... A piece of software I recently disassembled (trying to find out
why
> it would crash on load on this machine) looks for a special track in the
> last cylinder of a disk, and can be installed to a 1.2Mb floppy (the
INSTALL
> program writes the copy-protected track with a special 'installed' flag).
You may be able to overcome this byusing NOGUARD that came with COPYIIPC.
Also COPYIIPC had a NOKEY tsr that would allow a program installed on a HDD
to be run without haiving to insert the floppy.
>
> > This may have changed or may some OEM DOS does it differently, but what
> IBM
> > DOS DISKCOPY did/does is first it formats the disk then it copies all of
> the
> > files. It may or may not copy the BR. But as I recall, if I copied a 3.3
> > formatted diskette with MSDOS 5.0 installed and used 5.0 DISKCOPY, the
BR
> > would show the OEM ID as MSDOS5.0.
> My Amstrad 3.2 DISKCOPY copies the whole lot as a lump of sectors - the
boot
> sector and all. I know, since the 'Starting out with the PC' instructions
> include 'copy all four system disks supplied', two of which has a DOS Plus
> boot-sector while the others are MS-DOS - the boot sectors are copied
> correctly. It doesn't even adjust the data in case of a bad sector - so
if
> you copy a good diskette onto one with known bad sectors, the bad sector
> marks in the FAT disappear.
That is an OEM version. OEM versions do many things differently. I gave a
couple of examples in the message you are replying to. That DiSKCOPY would
have wroked fine with the copy protected disk I mentioned.
Pat
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