[hfs-user] Device (Driver) Descriptor Block and block size

Pierre Duhem Pierre Duhem <lsduhem@duhem.com>
Tue, 16 Mar 2004 09:00:48 +0100

Hi everybody,

A little question:

In the device/driver descriptor block (sector 0 of a disk), the first
three fields are:
   sbSig:         Integer;    {device signature}
   sbBlkSize:     Integer;    {block size of the device}
   sbBlkCount:    LongInt;    {number of blocks on the device}

For sbBlkSize, I always got 512 on magnetic hard disks and CD-ROMs
(magneto-optical disks are another matter). Now, what happens when the
disk contains more than 0xFFFFFFFF * 0x0200 bytes? This could be the
case with a DVD-ROM, for instance.

Best Regards
Pierre Duhem
Logiciels & Services Duhem, Paris (France)