Sharky Extreme - Hardware - Sharky Extreme Hard Drive Guide

As areal densities rose and rotational speeds jumped, hard drive manufacturers once again saw the need for a new standard. Similarly to UDMA/33, Ultra DMA/66 once again doubled the maximum capacity of the IDE chain. To do this, the clock speed halved, this time to 30ns, and a few problems arose. With such fast clock speeds across such a long bus, noise becomes an increasing problem. To combat this, an 80 wire model was created, and that is why UDMA/66 cables are different than anything we have seen for ATA drives in the last 6 or 7 years.

All UDMA/66 drives are capable of running on your legacy ATA chains, and you can even run legacy ATA drives on your UDMA/66 chains. Without the 80-wire cable, however, you will not get the "advantages" of the UDMA/66 devices.

UDMA drives offer more than just a bandwidth increase, however. They also increase the reliability of data, by adding a CRC calculation to the standard. Whenever data is sent to a drive operating in UDMA mode, it will error check the data, and if an error occurs, the data will be resent at a slower transfer mode. When all is said and done, however, in a single drive system, or even for most of us in a dual drive system, the gains are minimal, and upgrading the drive is likely more important than upgrading the controller.

UDMA/66 is just becoming available now, and drives are already being sold which support it. These drives are generally faster, as are most new drives when compared to their predecessors. This increase in speed is not a result of the transfer mode supported. The cost of upgrading to UDMA/66 is around $40, and should start appearing built into motherboards next quarter.

Cost
Firm infrastructure (motherboards have ATA connectivity built in)

Supports only a few drives at a time.
Slower protocol.
Slower drives available on the market.

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