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Table 11-3 Western Digital WD2160’s Physical and Logical Geometries

Note that, even with sector translation, the number of heads is greater than the allowed 16. So here’s where the magic of LBA comes in. The WD2160 is capable of LBA. Now assuming that the BIOS is also capable of LBA, here’s what happens. When the computer boots up, the BIOS asks the drives if they can perform LBA. If they say yes, the BIOS and the drive work together to change the way they talk to each other. They can do this without conflicting with the original AT BIOS commands by taking advantage of unused commands to use up to 256 heads. LBA enables support for a maximum of 1024 × 256 × 63 × 512 bytes 8.4-GB hard drives. Back in 1990, 8.4 GB was hundreds of time larger than the drives used at the time. Don’t worry, later ATA standards will get the BIOS up to today’s huge drives.

Not Just Hard Drives Anymore: ATAPI

ATA-2 added an extension to the ATA specification, called Advanced Technology Attachment Packet Interface (ATAPI), that enabled non–hard drive devices such as CD-ROM drives and tape backups to connect to the PC via the ATA controllers. ATAPI drives have the same 40-pin interface and master/slave jumpers as ATA hard drives. Figure 11-14 shows an ATAPI CD-RW drive attached to a motherboard. The key difference between hard drives and every other type of drive that attaches to the ATA controller is in how the drives get BIOS support. Hard drives get it through the system BIOS, whereas non– hard drives require the operating system to load a software driver.

Figure 11-14 ATAPI CD-RW drive attached to a motherboard via a standard 40-pin ribbon cable

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NOTE With the introduction of ATAPI, the ATA standards are often referred to as ATA/ATAPI instead of just ATA.

More Drives with ATA-2

ATA-2 added support for a second controller, raising the total number of supported drives from two to four. Each of the two controllers is equal in power and capability. Figure 11-15 is a close-up of a typical motherboard, showing the primary controller marked as IDE1 and the secondary marked as IDE2.

Figure 11-15 Primary and secondary controllers labeled on a motherboard

Increased Speed

ATA-2 defined two new PIO modes and a new type of DMA called multi-word DMA that was a substantial improvement over the old DMA. Technically, multi-word DMA was still the old-style DMA, but it worked in a much more efficient manner so it was much faster.

PIO mode 3: 11.1 MBps

PIO mode 4: 16.6 MBps

Multi-word DMA mode 0: 4.2 MBps

Multi-word DMA mode 1: 13.3 MBps

Multi-word DMA mode 2: 16.6 MBps

ATA-3

ATA-3 came on quickly after ATA-2 and added one new feature called Self-Monitoring, Analysis, and Reporting Technology (S.M.A.R.T., one of the few PC acronyms that requires the use of periods after each letter). S.M.A.R.T. helps predict when a hard drive is going to fail by monitoring the hard drive’s mechanical components.

S.M.A.R.T. is a great idea and is popular in specialized server systems, but it’s complex, imperfect, and hard to understand. As a result, only a few utilities can read the S.M.A.R.T. data on your hard drive. Your best sources are the hard drive manufacturers. Every hard drive maker has a free diagnostic tool (which usually works only for their drives) that will do a S.M.A.R.T. check along with other tests. Figure 11-16 shows Western Digital’s Data Lifeguard Tools in action. Note that it says only whether the drive has passed or not. Figure 11-17 shows some S.M.A.R.T. information.

Although you can see the actual S.M.A.R.T. data, it’s generally useless or indecipherable. Your best choice is to trust the manufacturer’s opinion and run the software provided.

ATA-4

Anyone who has opened a big database file on a hard drive appreciates that a faster hard drive is better. ATA-4 introduced a new DMA mode called Ultra DMA that is now the primary way a hard drive communicates with a PC. Ultra DMA uses DMA bus mastering to achieve far faster speeds than were possible with PIO or old-style DMA. ATA-4 defined