JJB wrote:
This is not true. With today's computers, all disks will operate at
their highest speed, not matter what other device they are paired
with.
Their transfer rate may be slowed down if *both* devices are
accessed at
the exact same time, but that's nothing to worry about generally. So
just
because you have a CD-ROM and an UDMA100 disk on the same channel,
it doesn't mean the UDMA100 disk will be slowed in nearly any
noticable
fashion.
I have an PC with mfg date of 5/2003 and the motherboard manually
has warning note about separating the cdrom drive to the secondary
IDE controller because it will force the IDE controller to step down
the max speed to the slowest device. This was not only for cdrom
drives but also mixing UDMA100 and UDMA66 and UDMA33 disk on any IDE
controller. IDE max controller speed is set by bios at boot time
after the probe post process completes. So just exactly what time
period are you referencing by "With today's computers"? DO you work
for Bios chip manufacture, or write the FBSD bios's boot probe code?
What is your technical background to make such an authoritative
statement in light of so much information to the contrary?
All you need to do is to Google for "hard drive cd-rom myth" and
you'll get plenty of places that explain this. I guarantee you
that a UDMA100 drive won't be set at PIO4 just because there's
a CD-ROM drive on the same channel. Your manual is probably talking
about exactly what I said - if both devices are accessed at the same
time, the transfer will occur at the slower rate. But that does not
mean either the bios or FreeBSD doesn't know that a UDMA100 drive
is out there. In fact, my FreeBSD has both a UDMA66 and 100 on it,
and FreeBSD knows all about the two. And if you are just getting
stuff from the hard drive (which is probably 95+% of the time),
then you have a perfectly functioning UDMA100 drive.
second device to the ribbon. Now if the devices are jumper as master
and slave it does make an difference which of the 2 closely spaced
nipples are used as the nipples have default meanings. And I believe
I don't think this is true either. I've hooked up a lot of drives
in my time, and I've never seen this. And no "build it yourself"
guide that I was able to find on the 'net mentioned anything at all
about which nipple to plug into the slave or master drive.
--
Jonathan Arnold (mailto:[EMAIL PROTECTED])
Daemon Dancing in the Dark, a FreeBSD weblog:
http://freebsd.amazingdev.com/blog/
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