Understanding PATA – CompTIA A+ 220-801: 1.5

The Parallel ATA interface standard is one of the most common legacy hard drive connection types. In this video, you’ll learn how to configure and connect PATA drives to your motherboard.

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Although PATA drives are not the most recent type of storage that you might find on today’s computers, you may still be asked to work on systems that have these legacy interfaces.

PATA stands for Parallel AT Attachment. It’s a callback to a previous PC version called the PC/AT. You might also hear this referred to as Parallel ATA, or simply ATA. The storage connection standard was created around 1999 by Western Digital, and it was originally called the Integrated Drive Electronics, or IDE. You might also see an updated version of this referred to as EIDE, which stands for Enhanced IDE.

There were a number of different PATA standards released through the years, ranging from 16 megabytes per second of throughput all the way up to 133 megabytes per second of throughput, which for the time was relatively fast. There were also enhancements to the standard that allowed us to connect more than just hard drives. We were able to connect CD-ROM drives and other peripherals as well. When SATA was introduced, the term ATA was modified to be Parallel ATA, so that you could discern the difference between a SATA and a PATA connection.

Here’s the type of cabling you might see if you open up an older computer that has one of these PATA drives inside. You first have the connection to the motherboard and then this ribbon cable, which is either a 40-wire cable or an 80-wire cable, will connect to the drives on the other side. You can see there are two interfaces available to connect these drives. On a 40-wire cable, device 0 is the closest one to the motherboard, and device 1 would be the farthest away. On an 80-wire cable, you’ll see that this is reversed. Device 0 will be farthest away from the motherboard, and device 1 will be closest.

As you can see from these cables, you can only support two drives on a single PATA a connection from your motherboard. If you need to connect additional drives, then you’ll need another PATA interface on your motherboard to be able to include additional drives on a separate cable.

Here’s a close up of the 40-wire cable and the 80-wire cable that you might find with PATA connections. The 80-wire cables are the most recent. They were added in newer versions of PATA to support higher throughputs. You’ll notice that the connectors are exactly the same. There are still 40 pins on each one of these. But the additional wires are used for grounding inside of the 80-wire cable to reduce the amount of crosstalk going over that connection.

Here’s the 40 pin PATA interface that you might find on a motherboard. You’ll notice it’s actually a 39 pin interface, because one of those pins is missing. This is intentionally keyed out, so that you can only plug the cable in one particular way.

If we go back and look at our previous cables, you can see this particular cable does have the key on that particular pin. Although you may find some cables that don’t have that key inside of them. And on the back of the PATA drive, you’ll see the missing pin inside of that cable connection as well. This is very similar to the SATA drive we looked at in a previous video, where we have our connection for our data. We have some jumpers that set configurations for the drive. And on most PATA drives, you’ll find Molex connections being used to provide the power.

When we move from parallel to serial with our storage drives, you’ll notice that the data cables changed quite a bit. The Parallel ATA, or PATA cable, is on the left, and the SATA data cable is on the right. You can see the SATA data cable is much smaller, takes up much less room, inside of a computer case. But it also allows for more airflow through the case for better cooling.