Path: utzoo!mnetor!uunet!seismo!sundc!pitstop!sun!decwrl!decvax!ucbvax!WATDCS.BITNET!DMIHOCKA
From: DMIHOCKA@WATDCS.BITNET (D Mihocka)
Newsgroups: comp.sys.atari.st
Subject: (none)
Message-ID: <8802280455.AA06317@ucbvax.Berkeley.EDU>
Date: 26 Feb 88 22:48:14 GMT
Sender: daemon@ucbvax.BERKELEY.EDU
Organization: The Internet
Lines: 36

Here's two differences I've run across between GEMDOS formatted disks and
MSDOS formatted disks:

1) size of FAT, the following information compares the disk usage of a
GEMDOS disk and MSDOS 3.3 disk, both formatted to 720K. The numbers in the
format a/b indicate the count of sectors for GEMDOS/MSDOS.
                  Start            Length
      FAT 1        1/1               5/3
      FAT 2        6/4               5/3
      Root Dir.   11/7               7/7
      Free Space 18/14         1422/1426
Note that the FAT on MSDOS is only 3 sectors long, since only about 1100
bytes are needed for the FAT. (Anyone know why GEMDOS needs more??). MSDOS
is thus able to cram an extra 4K of free space on each disk.

This leads to a big problem, which I believe someone was complaing about a
while ago. If you click on the A icon, and open a window for the A:\
directory (GEMDOS disk), then remove it and insert an MSDOS disk, press
Esc to get a new directory, you sometimes get 0 bytes in 0 items. If you
close the window and then click on A again, you'll get the correct
directory. It seems that GEMDOS does not check the location of the
directory when you insert a new disk. But it does when you first open the
window. (Why?????).

2) Volume label files have different attribute bytes. A normal file has an
attribute byte of $00. This means that it is not read-only, not a
directory, not a volume entry. When you format a disk on GEMDOS and give
it a name (a volume name), it creates a directory entry with an attribyte
byte of $08. MSDOS uses a value of $28.

This again causes some problems. If you do a directory of an MSDOS disk,
the volume name appears as a zero length file (which can be deleted). Why
does GEMDOS do this? Is it that hard to use the proper attribute byte an
the same sized FAT???

- Darek (arghhhhhhhh!!!)