Ultra ATA 66 Hard Drive Roundup - March 2000

Ultra ATA/66

Most of the IDE drives currently on the market are Ultra ATA/66 compliant now that the interface has become the new standard, surpassing the 3-year-old Ultra ATA/33 specification. As all ATA specifications call for backward compatibility, your new Ultra ATA/66 drive will work in older systems. This also means that older PIO and Ultra ATA/33 drives will maintain compatibility with newer Ultra ATA/66 hardware, as well. The requirements for running your Ultra ATA/66 hard drive at Ultra ATA/66 speeds, are an Ultra ATA/66 capable motherboard or IDE controller card and that you use an 80-pin IDE cable instead of the older 40-pin version.

While the pin designations remain the same as with regular IDE cables, at Ultra ATA/66 speeds signal quality issues become a major concern. It is due to this fact that your system needs to determine if you are using the newer 80-pin cable, or older 40-pin cable, before it will enable Ultra ATA/66 mode. While the pin designations are the same, as stated above, one of the lines is broken, where in the 40-pin cable, the connection is unbroken. It is this broken connection that the system will pick up on, to determine if you are using the correct 80-pin cable needed for Ultra ATA/66 operation.

At higher data transfer speeds, cross talk and interference between the data lines impedes the flow of error free communication. To help ensure the integrity of the data signals passing from your drive to the controller, the Ultra ATA/66 standard calls for an addition of a grounding wire to be paired with each one of the signal wires in the interface cable. These 40 grounding wires are only connected at one end and are left un-terminated at the other end to prevent a ground isolation loop from occurring. If you use the standard 40-pin IDE cable with an Ultra ATA/66 drive, your drive will revert to Ultra ATA/33 speeds.

It is due to this “quieter” signal that Ultra ATA/66 is possible. The drive controller must determine whether the data lines have switched to a high or low state before it can read a signal off them. In order to assure a correct reading, the controller must wait awhile after a data burst in order to ensure the signals have settled down to their proper state. This is known as the setup time. With the addition of the 40 extra ground cables, thus filtering out external noise and cross talk, the setup time can in effect be halved. This halving of the setup time is what actually enables Ultra ATA/66 to be so easily implemented without any further significant changes to the Ultra ATA standard.

Now that we have a bit of background, let us introduce you to the drives that are part of this roundup. The drives selected for this round up represent what we consider would be the current choice one would make if upgrading or building a new system today. The only requirements for this roundup were that the drives have 25 GB or more of storage space and that they are compliant with the Ultra ATA/66 standard.