The host controller circuitry resides on the motherboard, or in the case of an IDE/ATA accellerator/expansion card, on the card. The drive controller circuitry is (obviously) on the drive.

Look on the motherboard or consult your motherboard's documentation. Traditionally there are two IDE channels (Primary and Secondary) on a motherboard.

You can connect a maximum of two devices to any given IDE channel.

I see many 40 pin cables coming out of the motherboard to which I can connect hard disks, does each of them represent a IDE channel ?

It really depends on the exact model of your motherboard. Do you have any info/specifications for the motherboard?

Here is the main board info

Board: Hewlett-Packard 085Ch
Serial Number: SGH442011L
Bus Clock: 800 megahertz
BIOS: Hewlett-Packard 786B2 v1.11 07/10/2003


and this is the controllers info

Standard floppy disk controller
Intel(R) 82801EB Ultra ATA Storage Controllers - 24D1
Intel(R) 82801EB Ultra ATA Storage Controllers - 24DB
Primary IDE Channel [Controller] (2x)
Secondary IDE Channel [Controller] (2x)


Thanks

I couldn't find specs for that particular motherboard, but from what you posted, you appear to have (2) 82801EB controllers on the motherboard. Each 82801EB controller has a Primary and a Secondary channel, so you should see 4 IDE/ATA connectors on the motherboard. Does that sound about right?

Since each channel of each controller can handle two drives, it looks like you should be able to connect 8 drives to that system.

thanks a lot for your help, the one from which I posted the specs is my office pc so I don't want to open its case

however in my home pc I see only

Primary IDE Channel [Controller] (2x)
Secondary IDE Channel [Controller] (2x)


and it has two ide cables, so you are right

Right- one cable for the controller's Primary channel, one cable for the Secondary channel. That means that you can connect two drives to each cable for a total of 4 devices.

which side of an ide cable should be nearest to the power supply on the hard if anyone could help that would be nice .

There is no power supply on the hard drive itself, but if you mean the power connector, then the side of the cable which has the colored stripe along it would conventionally be nearest that connector. The stripe marks the cable's #1 wire/pin, and that should correspond to Pin #1 of the drive's IDE connector.

You can (and should) check the drive manufacturer's website for cabling/connection info for the specific model of drive, because the orientation of the IDE cable may not be as I described for every make/model of drive.