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Figure 11-16 Data Lifeguard

Figure 11-17 S.M.A.R.T. information

Ultra DMA mode 0: 16.7 MBps

Ultra DMA mode 1: 25.0 MBps

Ultra DMA mode 2: 33.3 MBps

* * *

NOTE Ultra DMA mode 2, the most popular of the ATA-4 DMA modes, is also called ATA/33.

INT13 Extensions

Here’s an interesting factoid for you: The original ATA-1 standard allowed for hard drives up to 137 GB. It wasn’t the ATA standard that caused the 504-MB size limit; the standard used the old AT BIOS, and the BIOS, not the ATA standard, could support only 504 MB. LBA was a work-around that told the hard drive to lie to the BIOS to get it up to 8.4 GB. But eventually hard drives started edging close to the LBA limit and something had to be done. The T13 folks said, “This isn’t our problem. It’s the ancient BIOS problem. You BIOS makers need to fix the BIOS.” And they did.

In 1994, Phoenix Technologies (the BIOS manufacturer) came up with a new set of BIOS commands called Interrupt 13 (INT13) extensions. INT13 extensions broke the 8.4-GB barrier by completely ignoring the CHS values and instead feeding the LBA a stream of addressable sectors. A system with INT13 extensions can handle drives up to 137 GB. The entire PC industry quickly adopted INT13 extensions, and every system made since 2000–2001 supports INT13 extensions.

ATA-5

Ultra DMA was such a huge hit that the ATA folks adopted two faster Ultra DMA modes with ATA-5:

Ultra DMA mode 3: 44.4 MBps

Ultra DMA mode 4: 66.6 MBps

* * *

NOTE Ultra DMA mode 4, the most popular of the ATA-5 DMA modes, is also called ATA/66.

Ultra DMA modes 4 ran so quickly that the ATA-5 standard defined a new type of ribbon cable that could handle the higher speeds. This 80-wire cable still has 40 pins on the connectors, but it also includes another 40 wires in the cable that act as grounds to improve the cable’s capability to handle high-speed signals. The 80-wire cable, just like the 40-pin ribbon cable, has a colored stripe down one side to give you proper orientation for pin 1 on the controller and the hard drive. Previous versions of ATA didn’t define where the various drives were plugged into the ribbon cable, but ATA-5 defined exactly where the controller, master, and slave drives connected, even defining colors to identify them. Take a look at the ATA/66 cable in Figure 11-18. The connector on the left is colored blue (which you could see if the photo were in color!)—and you must use that connector to plug into the controller. The connector in the middle is grey—that’s for the slave drive. The connector on the right is black—that’s for the master drive. Any ATA/66 controller connections are colored blue to let you know it is an ATA/66 controller.

Figure 11-18 ATA/66 cable

ATA/66 is backward compatible, so you may safely plug an earlier drive into an ATA/66 cable and controller. If you plug an ATA/66 drive into an older controller, it will work—just not in ATA/66 mode. The only risky action is to use an ATA/66 controller and hard drive with a non-ATA/66 cable. Doing so will almost certainly cause nasty data losses!

ATA-6

Hard drive size exploded in the early 21st century, and the seemingly impossible-to-fill 137-GB limit created by INT13 extensions became a barrier to fine computing more quickly than most people had anticipated. When drives started hitting the 120-GB mark, the T13 committee adopted an industry proposal pushed by Maxtor (a major hard drive maker) called Big Drive that increased the limit to more than 144 petabytes (approximately 144,000,000 GB). Thankfully, T13 also gave the new standard a less-silly name, calling it ATA/ATAPI-6 or simply ATA-6. Big Drive was basically just a 48-bit LBA, supplanting the older 24-bit addressing of LBA and INT13 extensions. Plus, the standard defined an enhanced block mode, enabling drives to transfer up to 65,536 sectors in one chunk, up from the measly 256 sectors of lesser drive technologies.

ATA-6 also introduced Ultra DMA mode 5, kicking the data transfer rate up to 100 MBps. Ultra DMA