1 Jan
2010
1 Jan
'10
11:35 p.m.
On 1 Jan 2010 at 19:40, Josh Dersch wrote:
Very interesting, I had no idea. Looks like Windows
95/98 only:
http://support.microsoft.com/kb/148637.
Never heard about this before. Sounds like a useful idea poorly
implemented (cue snarky comments). Recent Windows releases definitely
don't do this or I'd have had a lot of trouble with my IBM PS/2
refdisks...
Modern (1.2M 5.25 and 1.44M 3.5) floppy drives come with a "disk
changed" detection feature (really a "the drive gate was opened--
you'd better check" status). 360K and some 720K drives do not.
Microsoft apparently wanted a volume tracking feature that would work
for all removable media and so devised the above-described method;
words in the KB say that the VSN in the boot sector isn't reliable
enough and the implementors apparently didn't want to take the CP/M
route of checksumming the first few directory entries of a disk.
One wonders why MS couldn't have picked somewhere else to write if
they really needed to do it. We used to warn our customers that if
they were set on using Win95 to browse floppies to make sure that
write protect was set on every floppy they looked at--or to disable
writing (by clipping the WG* pin on the floppy connector)
permanently on the floppy drive.
--Chuck