Does IDE controller on BX mobos have independent device timing?

[jrichrds]

I have an UDMA33 device and a PIO Mode 4 device hooked up to the same channel on the integrated IDE controller of a BX Mobo. Is this a bad idea? I don't know whether this IDE controller has independent device timing like all the current controllers.

 

[AndyHui]

All PIIX4 SouthBridge Controllers feature independent IDE Device timing.

This means that the 430TX, 440LX, 440BX chipsets, all allow each individual device on an IDE channel to operate at its full speed without being affected by another device.

The 430HX, 430VX and 440FX chipsets feature the older PIIX3 SouthBridge and do not support independent IDE Device timing.

 

[jrichrds]

Thank you Andy!

Besides offering higher transfer rates (ATA/66, ATA/100), have controllers improved in any other way? (e.g. ability for both devices on one channel to be active at same time?)

 

[AndyHui]

Nope. It's the way IDE works. The Master-Slave policy only allows one active device at a time.

You will need to go SCSI for multiple simultaneously active devices. Serial ATA is a little different, since there is only one device on a single channel.

 

[Peter]

No, this is impossible. The mainboard chipset merely provides the bus bridge from PCI to IDE. The IDE drives itself follow the same arrangement we had back in 1983 in the first IBM AT - one controller steering two drives. Only that the controller isn't an ISA card anymore, and has been pulled into the (Master) drive. The IDE cable is ISA on steroids, but in the programming model, no change ever. There is only one active controller on a given IDE channel - in the Master drive. It controls both its own and the Slave's storage media, and can only handle one request at a time.

The outcome is, if you use one of the drives at 100 percent, then the other drive will be unusable, no matter how fast the interface is in comparison to the drive's actual throughput.
regards, Peter

 

[Peter]

hehe, Andy was faster ... Serial ATA is different in that you can't have a Slave drive anymore, and that the IDE signalling goes through a serial transceiver pair at both ends. Other than that, same old crap.

regards, Peter

 

[jrichrds]

Thanks guys. 🙂 Really informative.

A couple last questions...
1. Is ATA/66-100-133 more reliable than ATA/33? I hear the former has CRC error checking algorithms built-in? I'm currently running a 5400rpm ata-100 HD with the BX ide controller, but would throw in a Promise ATA-100 controller if there was a reliability benefit of some sort.

2. I have S.M.A.R.T. monitoring enabled in my BIOS. Does that mean the BIOS will pop up a message on my screen when SMART finds something wrong with my HD? Or do I need an accompanying Windows program for this to work?

 

[tcsenter]

1. Is ATA/66-100-133 more reliable than ATA/33? I hear the former has CRC error checking algorithms built-in? I'm currently running a 5400rpm ata-100 HD with the BX ide controller, but would throw in a Promise ATA-100 controller if there was a reliability benefit of some sort.

All HDD controllers and chipsets capable of Multiword DMA Mode-2 or higher implement CRC32 error checking, unless you turn off DMA mode transfers.

2. I have S.M.A.R.T. monitoring enabled in my BIOS. Does that mean the BIOS will pop up a message on my screen when SMART finds something wrong with my HD? Or do I need an accompanying Windows program for this to work?

You need a SMART utility, your BIOS will do nothing.

 

[Peter]

Yes it does. At some point or another during POST, at least AMI BIOSes perform a basic SMART diagnostic and then say "SMART enabled - Status OK" (or not 🙂). It's either on the POST screen amidst the drive detection messages (up to AMIBIOS 7.x) or on the system configuration summary screen (on newer ones).

regards, Peter

 

[jrichrds]

tcsenter: thanks for the CRC clarification

Peter: Ohh okay, so it checks during the POST process. Makes sense.

 

[tcsenter]

Yes it does. At some point or another during POST, at least AMI BIOSes perform a basic SMART diagnostic and then say "SMART enabled - Status OK" (or not ).

Thanks, I haven't much experience with very recent BIOS builds and much less with AMI BIOS. The AWARD BIOS I've seen just report "SMART Monitoring....Enabled" or "SMART Monitoring....no SMART capable devices found" or something to that effect when enabled in BIOS. With those you need a utility.

tcsenter: thanks for the CRC clarification

For further clarification, the transfer mode must be Multiword DMA Mode-2 or higher, not simply that the controller and chipset must support it. If the system is operating in a lesser mode, or DMA is disabled, there is no CRC32 checking.