16 Jan
2005
16 Jan
'05
10:56 a.m.
On Sun, 16 Jan 2005, Vintage Computer Festival wrote:
The whole impetus behind this was that I was trying to
read an old 360K
(might even be 320K or even 180K, I'm not sure) disk and while I could
read the directory, none of the files larger than say a cluster could be
read. I attributed this to the drive not being a "true" 360K drive.
Are you sure that the disk is in a PC-DOS format?
If the diskette is 96tpi (720k 5.25) such as PC-JX, Toshiba 300, . . .
then track 0 will be readbale, but the other tracks won't.
OR,...
if the boot sector, and/or the first byte of the FAT is wrong/different,
then DOS will misunderstand the disk parameters and screw up.
Fred seems to be the Guru with regards to floppy
formats, and perhaps I
misinterpreted what I read, but I recall him bringing up a scenario in
which a disk formatted as 360K on a newer drive would not be readable on
an "actual" (i.e older) 360K drive, or the other way around, or something.
The most common problem is that 96tpi drives, both 720K and 1.2M, write a
narrower track than 360K (about 1/6 mm wide at about 1/4mm center to
center, v about 1/3mm wide at about 1/2mm center to center)
Because of that, when a 96tpi drive REWRITES a track that was previously
written by a 48tpi drive, it might not reliably erase all of the edges of
the old track. In such a case, it should still read reliably in a 96tpi
drive, but not necessarily reliably in a 48tpi. OR,... if you format a
VIRGIN (or bulk erased) disk as 360 in a 1.2, it should read OK.
--
Grumpy Ol' Fred cisin(a)xenosoft.com