Ultra ATA-66

More and faster drives!

Another thing you'll notice is that there are a total of 4 IDE looking ports. This allows connectivity of up to eight IDE devices! Connecting all eight, however, would require some IRQ configuration. Why are there four IDE connections? For the Ultra ATA 66, of course!

ATA66 in white...

...floppy and ATA33 in black

Ultra ATA-66

Ultra DMA 66 is the next level of hard drive transfer modes. As you may have read in our FS Hard Drive Guide, the last IDE/ATA transfer mode until recently was the ATA 33 mode, which specifies a maximum throughput of 33MB/s. The ATA 66 spec is the next step, which logically specifies 66MB/s as the maximum throughput. There are a few requirements in order to use Ultra ATA-66:

1. The drive has to support Ultra ATA-66.
2. The motherboard and its accompanying BIOS must support Ultra ATA-66, unless an add-on controller card is used.
3. The operating system must support Direct Memory Access (DMA).
4. The cable must be 80 conductor. Its length can not exceed 18 inches.

The first three requirements are self-explanatory. The drive and motherboard must support the Ultra ATA-66, while the operating system must support the process that Ultra ATA-66 uses to transfer data through memory. The fourth requirement, regarding the cable type and length, is more reminiscent of SCSI. Actually, this is not far from the truth.

Cabling concerns

As we use faster and faster data transfers in our hard drives, we are sending electric signals over the cabling at faster speeds. The chance of having some kind of interference or signal degradation is real. Although it won't destroy your system, it might cause bad reads and writes to your hard drive. The cable requirements address both of these concerns: interference and degradation.

80-conductor diagram

ATA66 vs. ATA33

Signal interference, which is often called "crosstalk" is when electric signals are high powered enough that they affect other signals. This is especially true in cables where wires run next to each other, like hard drive cables. The 80 pin Ultra ATA-66 cable reduces crosstalk by adding an additional 40 ground lines. Electric signals lose power the further they travel.

Signal degradation is when an electric signal traveling from one point to another loses enough of its power, or charge, that by the time it reaches its destination, it can be misread. The signal degradation issue is dealt with by specifying the maximum length that the cable should be, which will insure that the signal is solid in transit.

Cable coloring

No, it's not an I-Mac marketing scheme. The Ultra ATA-66 cable has colored connectors. That is because these connectors mean different things. The blue connector must be plugged into your motherboard. The black connector attaches to the master hard drive, and the gray connector attaches to the slave drive. The reason why these connectors must be matched to their proper connectors is because the cable has a small polarization tab which is located on the connector's head. This must fit to the matching slot on the other end of the connection, or it won't work!