Ultra ATA/66 versus Ultra ATA/33 Comparison

Implementing Ultra ATA/66

Before we get too far into our discussion, there are a few concerns you should be familiar with before implementing Ultra ATA/66 into your system. Some of the obvious considerations are that you have an Ultra ATA/66 compatible motherboard or controller and Ultra ATA/66 hard drive, and that you utilize an 80 conductor, 40-pin IDE cable. But there are some other considerations too.

As most of you are well aware, a single IDE channel can support up to two devices maximum. In order to operate your drive at Ultra ATA/66 speeds, all of the devices on that channel must also be Ultra ATA/66 compliant. This means that you will not be able to keep your old PIO mode 4 CDROM drive or DVD drive on the same channel as your new Ultra ATA/66 hard drive without hindering performance.

At first this may not seem to be much of an issue, until you stop to consider that devices on IDE channels are usually arranged so as to provide optimum performance. Let’s say you have one hard drive, a CD/DVD player and a CDRW drive in your system. The optimum configuration has been to place the hard drive as master on the primary IDE channel, the CD or DVD reader as slave on the primary channel, and the CDRW drive as master on the secondary IDE channel. Those of you with a second hard drive would follow the above setup, except the second hard drive would be master on the secondary IDE channel and the CDRW drive would then run as slave.

The advantages to such a setup are that most drive-to-drive transfers could be performed using both IDE channels, as only one device can be active at a time on one channel. So using the above setup, transfers from your hard drive to your CD burner, or transfers from your CD/DVD drive to your CD burner, would utilize both channels and you would realize a greater data throughput. If you needed to install programs off of a CD, you could simply use your CDRW drive as the reader, thus keeping reads and writes on separate channels for slightly quicker installation times. Those of you with the second hard drive on the secondary IDE channel could also see gains by placing your swap file on the second hard drive as well. This would allow your system to access data from your main hard drive and swap file at the same time, increasing performance slightly. This arrangement works out quite well for the average user.

Now enter Ultra ATA/66 into the above configuration and we start to run into trouble. Assuming our system is Ultra ATA/66 compatible and that we are using the proper 80-conductor cables, we still have the problem of a non-Ultra ATA/66 device dragging our performance down. If we had 2 Ultra ATA/66 hard drives, we could put them both on the same channel and then put the CD devices on the secondary channel, but then that negates any of the benefits we previously gained by using the secondary hard drive for the swap file, or for CD to CDRW transfers. While this may not be a problem in certain situations, it does cause grief for someone trying to maintain the optimal setup. Unless you use an add-in IDE controller card, such as those manufactured by Promise, you are limited in your configuration choices, and no matter what you choose, your performance will be less than optimal.

While this article does not intend to provide the magic bullet to solve the above dilemma, it should help to shed some light on just how drastic of a performance hit you will see if you choose one configuration over the other.