21 May
2003
21 May
'03
11:59 a.m.
On Wed, 21 May 2003, Tony Duell wrote:
No, but "DD" drives initially, for obvious reasons, did not have a switch.
Many people who were oblivious to differences in reliability used HD
diskettes in DD machines, and thought that they worked correctly.
I think that THAT is what he meant by "everybody went to HD" in reference
to his Atari, Amiga, etc. experiences.
And, I can easily show you "HD" drives that do not have a switch! IBM did
not put a switch in their original "1.44" drives in PS/2's. Some users of
those claim that DD diskettes work correctly. (and then later complain
about the COMPUTER being "unreliable")
At no point has the price differential been so extreme as to justify using
the wrong diskette on a regular basis. Admittedly, there can be
"emergencies", where the correct diskette is unavailable that might result
in a need to make do with a wrong one.
My atari ST,
Amiga 500,1200 Use them. DD disk drives were only used for a
few years so everybody went to HD production (still in use).
2 points :
1) The HP 9114 drive that I mentioned used _original_ DD drives, rotating
at 600rpm. When these drives were designed, the HD disk hadn't been
thought of...
2) Even now, HD drives have a switch to detect the hole in the HD disk,
and one thing this switch does is to change the head write current to
cater for the different coercivity of the DD and HD media.
Have you got _proof_ (either from schematics, or by actually measuring
the write current in an opertation drive) that the write current is the
same for both DD and HD disks in a correctly-functioning name-brand
drive? Becasue I am darn sure it isn't!