ATA66 on the same ribbon as ATA100

[Cesaro]

I was wondering if someone could give me some technical information on what happens when an ATA66 drive and an ATA100 drive share the same IDE channel. I've gotten mixed answers from people. Some telling me that the 66 device will still run at 66 while the 100 runs at 100, while others say that both drives will run at 66. I was HOPING that they would both be allowed to run at their own speeds, and that the 66 would just be slightly out of sync, but still serviced by the IDE controller. Its interrupts would be off the mark, but it would service and be serviced as fast as it could handle. Some people have told me this was false. Could someone give me some actual technical information on what happens there? Thanks.

=Cesaro

 

[Superdoopercooper]

There will be a big fire and your computer will cease to exist.

Actually, my first guess would be that the IDE channel will run only as fast as the slowest component on the ribbon cable.... Because the signal supplying the faster drive also has to work with the slower, I'm thinking you'll get 66 from both.

The good news is that most drives don't REALLY operate much faster than ATA33... meaning your ATA100 drive will not have much more transfer speed than 33MB/sec. I think the best 7200rpm drives are around 43MB/s. So... ATA66/AT100... same difference

 

[Cesaro]

Yeah, trying to find technical info on how this process works is a bear though.

I've done some more searching and most of the common folk seem to say everything on the channel will run as slow as the slowest device. That seems to be the first conclusion....

I dug a little deeper and found other people saying that all "recent" controller chipsets allow for a per-device speed setting. Since an IDE device will essentially lock the ribbon during it's operation this one seems more feasible. I would certainly hope that the chipset would handle having two drives of differing speeds without downgrading one...

I know the performance boost isn't anything to bark at, but still....every little bit helps right?

=Ces

 

[ucla88]

modern ide controllers suport independent device timing, which will allow different devices to run at their respective levels,
(of course, with ide, only one drive is transferring data via the cable anyway). so, yes, you can run an ata-66 and ata-100 device on the same chain without the ata-100 device dropping to ata-66. this does NOT apply if you are running one of your devices in pio mode (rare, unless you have a very old device or a driver issue)