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Old March 9th 04, 11:15 PM
kony
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On Tue, 9 Mar 2004 13:08:58 -0600, "*Vanguard*"
wrote:

"Steve James" said in :
Hi

I have two HD's on the same IDE channel, I think one is faster than
the other (ATA and RPM), will the fastest one be 'held back' by the
slowest one or not ? I have my O/S and program files on the main
(fastest) drive and only use the slower one for storage and the
pagefile. (to reduce head travel)

MTIA

Steve


It depends on what motherboard chipset you use. I had a 3+ year-old
Pentium 3 800MHz Slot1 (SECC2) system that used the AOpen AX6BC
motherboard which uses Intel's 440BX chipset. The IDE controller
operated only in single mode; i.e., it would get set for whatever was
the slowest reported device. Doesn't matter what the IDE ports were set
for in the OS. The IDE controller provides 2 channels. For that
system, it was important to match the ATA spec of the devices on each
IDE port and try to NOT mix ATA (hard drive) and ATAPI (CD-ROM drive)
devices on the same port. CD-ROM drives then and still only operate up
to UDMA-33. Putting an UDMA-33/66/100/133 hard drive on the same IDE
channel as, say, a UDMA-33 CD-ROM drive, had the controller operate at
the least-common-denominator of whatever was the slowest device on that
channel so the hard drive would also operate at UDMA-33.


Ummmm, that had nothing to do with the 2nd device, the 440BX chipset only
supports up to ATA33, there is no possible way for any device in any
possible configuration to run any faster than ATA33 from it's onboard
controller.

snip


So for the old chipsets, they could operate the 2 IDE channels at
different modes (i.e., speeds) but they could only use the lowest
device's mode for all devices on the same channel. One channel could
run in one mode and the other channel could run in a different mode, but
a channel itself could only operate in one mode. Now comes along newer
chipsets that can support multiple concurrent modes on the same IDE
channel.


That happened around 1994, IIRC.