device speeds on same IDE channel

[ZippyDan]

i heard a long time ago that an IDE channel will run at the speed of the slowest device (master or slave). i suppose this refers to the transfer speed (AtA33, AtA100, PIO4, etc), and would not affect speed gains resulting from RPM, seek time, etc? i think back when i heard this, ata33 hadnt even been invented so it may be an old rule.

im asking because i am planning on putting a 20GB 7200 rpm HD on same channel as an 80GB 5400 rpm HD and i want the 20GB drive to be as speedy as it is supposed to be

now i am aware that an IDE channel can only read or write at any one time, so transferring data btwn devices on same channel (from 80gb to 20gb), or utilizing data from both drives at same time, will incur a performance hit... im ok with that

~Zippy!

 

[ZippyDan]

~Zippy!

 

[tart666]

The transfer mode will be limited by the slowest drive on the chain, be it ATA66 or ATA100.

Neither of your drives will stress even ATA66 (even both at once), so you needn't worry.

 

[thorin]

Sorry Tart666 but your wrong dude....

Most modern motherboards and controllers support independant device timing that means you can put a ATA33 drive on a cable (80wire) with a ATA133 drive and they won't affect each other. The only exception is PIO Mode devices.

Thorin

 

[tart666]

Nice work thorin, thx (yes, edited for spelling)

 

[senior guy]

Totally agree with thorin's reply. What you (ZippyDan) heard a long time ago, was true a long time ago - but no longer!

 

[ZippyDan]

so the conclusion is that putting a (wild guesstimate figures):

20gb, 7200 rpm, 9ms seek time, ATA100 HD

and a

80gb, 5400 rpm, 10ms seek time, ATA66 HD

on the same channel will have absolutely 0 effect on each other and both will run at full speed, unless i am trying to read/write from one to the other, or both at the same time?

~Zippy!

 

[ZippyDan]

and even though this is off topic, ive wondered this for a while... most CD-ROM drives (and CD-RW or DVD drives for that matter), do ATA33?? i guess i could check in bios, but last i cared to check i remember seeing PIO (but isnt PIO 5 = DMA33?)

~Zippy!

 

[TheCorm]

Thats right Zippy, like people have said, it used to be that transfer speeds worked in the way that they both ran at the slower devices interface. Spin speed (rpm) has never been affected by this though.

Never heard of anything designated as PIO 5 before. all modern CD-ROM drives will be ATA33, some DVD-ROMS and CD-Writers are even ATA66 but it makes no difference, if a hard drive can't fully utilise ATA66 then how will a CD-Writer?

Corm

 

[bgeh]

yup, now new mobo's support independent device timings(or something like that), so if you have a ATA 66 device and a ATA 100 device, they will run on ATA 66 and ATA 100 respectively.

 

[LED]

This subject has been repeatedly asked with repeated corrections...nothing changes...
thorin has this been put in the FAQ's yet cause I couldn't find it.
Andy it probably won't settle the issue from being brought up again but it sure would help

 

[thorin]

Originally posted by: LED
This subject has been repeatedly asked with repeated corrections...nothing changes...
thorin has this been put in the FAQ's yet cause I couldn't find it.
Andy it probably won't settle the issue from being brought up again but it sure would help

I'll make sure the HD Interfaces and Standards FAQ gets updated shortly.

Thorin