IDE is the type of connections used for almost all drives but 3 1/2" floppy drives. Typically a system can only have four of these type of devices at a time. On most modern motherboards you will find two IDE connectors, probably labeled as 'Primary' and 'Secondary'. Some newer motherboards will have two sets, we will discuss this later. The connectors will have two rows of 20 pins each, although one row may have a middle pin missing (this is OK). The connector may also have a gap in the middle of one side and this is OK also. The missing pin and/or the gap are to help make sure you install the cable in the right direction. The connectors may also have a number '1' printed to one end of the connector. This '1' denotes that the pins are numbered starting from that side, that is important as your cable has a red stripe down one side for pin '1'. With two connectors and only four devices, that leaves us with two devices per connector. Your cable will have two or three connectors, most have three, one is for the motherboard the rest are for your disk drives.

Your drives don't care whether they are plugged into the 'Primary' or the 'Secondary' IDE connector. They do care if they are 'Master' or 'Slave'. The drive or manual that came with the drive will give directions on how to set the jumpers to set the drive as 'Master', 'Slave' or 'Cable Select'. We will ignore the 'Cable Select' mode, because it doesn't deal with anything we will be doing. One of the drives that you connect the cable must (although sometimes they still work) be set as 'Master'. If you connect a second drive to the same cable, then set it to 'Slave'.

You will want to make sure that the harddrive you will be using as your C: drive is connected to the 'Primary' IDE connector and should be setup as the 'Master' device on the cable. If you are only installing one other IDE device into your computer the put it on the 'Secondary' connector. This is because the IDE connection will slow down to the slowest of the two devices. The speed the IDE connection will run at is based on the interface speed of the two devices. Most hard drives today, are labeled as Ultra 100, or Ultra 66 (or ATA/100, UDMA100 and ATA/66, UDMA66 respectively), this is type of connection the device makes with your computer. Most CD-ROMs and DVD-ROMs are Ultra 33. There are no compatibility issues with mixing different speed drives. If your motherboard only supports UDMA33, and you put an UDMA100 drive and a UDMA33 drive on the primary IDE connection, the UDMA100 drive won't be hindered by the UDMA33 drive since the motherboard can't go any faster than UDMA33.