30 Jun
2000
30 Jun
'00
6:18 a.m.
> Considering the 96tpi DD 5.25" disk and the
3.5" DD disk, they have the
> same number of cylinders (80), the same number of heads (2), the same
> number of sectors/track (9), the same rotational speed (300 rpm) ,etc. So
> why isn't the capacity _exactly_ the same?
It is. The computer can't tell them apart.
Prior to DOS 3.20 (particularly in 2.11), many OEMs
started using
5.25" 720K drives and 3.5" 720K drives. But because it was not sanctioned
by IBM, there was no standardization, and there were many mutually
incompatible formats. Starting with 3.20, the format is standardized.
Thats the core issue: IBM didn't use 720K prior to DOS 3.2 - DOS
itself was able to support almost any format you may think of, and
many manufacturers did. In case of DOS, IBM was only one of many,
and not the sole supplier of everything.
Gruss
H.
--
VCF Europa 2.0 am 28./29. April 2001 in Muenchen
http://www.vintage.org/vcfe
http://www.homecomputer.de/vcfe