On Tue, 22 Dec 2015 14:44:31 -0500 (EST), Sven Hartge wrote: > > In ye olde days (pre-Windowsm 98) some programs (I think Photoshop did > it.) wrote licence data into that space, because it was unused. The copy > protection scheme of some games also tried to hide information there. >
I can think of some other cases. Back in the day when most BIOSes had a head limit of 16, thus limiting the size of a hard disk addressable via BIOS Int 13h functions 02h and 03h to 504MiB, programs such as Ontrack Disk Manager could be installed to circumvent this restriction. They would hook the BIOS to increase the head limit to 255. I believe this was accomplished by putting the BIOS hook program in the boot sector and moving the original boot sector to the second sector (CHS value 0:0:2). Also, in the days of IBM 386 microchannel machines, such as the IBM PS/2 model 70, IBM sold a memory board that initialized after POST by using a similar boot hook. Around that same time period, Novell Netware was known to also use an unallocated sector, perhaps for licensing, copy protection, etc. These schemes all conflicted with each other of course. As I say in my lilo web page, there are no rules for the use of unallocated sectors. And grub-legacy and grub-pc (by default at least) now do a similar thing. They store information in unallocated sectors. That's one of the reasons (but not the only reason) that I switched back to LILO. -- .''`. Stephen Powell <zlinux...@wowway.com> : :' : `. `'` `-