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geometry. In most cases, these three critical values are referred to as CHS. The three values are important because the PC’s BIOS needs to know the drive’s geometry to know how to talk to the drive. Back in the old days, a technician needed to enter these values into the CMOS setup program manually. Today, every hard drive stores the CHS information in the drive itself, in an electronic format that enables the BIOS to query the drive automatically to determine these values. You’ll see more on this later in the chapter, in the “Autodetection” section.

Two other values—write precompensation cylinder and landing zone—no longer have relevance in today’s PCs; however, people still toss around these terms and a few CMOS setup utilities still support them—another classic example of a technology appendix. Let’s look at these two holdouts from another era so when you access CMOS, you won’t say, “What the heck are these?”

Write Precompensation Cylinder Older hard drives had a real problem with the fact that sectors toward the inside of the drives were much smaller than sectors toward the outside. To handle this, an older drive would spread data a little farther apart once it got to a particular cylinder. This cylinder was called the write precompensation (write precomp) cylinder, and the PC had to know which cylinder began this wider data spacing. Hard drives no longer have this problem, making the write precomp setting obsolete.

Landing Zone On older hard drives with stepper motors, the landing zone value designated an unused cylinder as a “parking place” for the read/write heads. As mentioned earlier, before moving old stepper motor hard drives, the read/write heads needed to be parked to avoid accidental damage. Today’s voice coil drives park themselves whenever they’re not accessing data, automatically placing the read/write heads on the landing zone. As a result, the BIOS no longer needs the landing zone geometry.

Essentials

Solid-state Drives

Booting up a computer takes time, in part because of the time it takes for a traditional hard drive to spin up and for the read/write heads to retrieve the data off the drive to load the operating system and drivers into RAM. All of the moving metal parts of a platter-based drive use a lot of power, create a lot of heat, take up space, wear down over time, and take a lot of nanoseconds to get things done. A solid-state drive (SSD) addresses all of these issues nicely.

In technical terms, solid-state technology and devices are based on the combination of semiconductors, transistors, and bubble memory used to create electrical components with no moving parts. That’s a mouthful! Here’s the translation.

In simple terms, SSDs (see Figure 11-6) use memory chips to store data instead of all those pesky metal spinning parts used in platter-based hard drives. Solid-state technology has been around for many moons. It was originally developed to transition vacuum tube-based technologies to semiconductor technologies, such as the move from cathode ray tubes (CRTs) to liquid crystal displays (LCDs) in monitors. (You’ll get the scoop on monitor technologies in Chapter 19, “Video.”)

Figure 11-6 A solid-state drive (photo courtesy of Corsair)

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NOTE With solid-state drives coming into more regular use, you see the initials HDD used more frequently than in previous years to refer to the traditional, platter-based hard drives. Thus we have two drive technologies: SSDs and HDDs.

Solid-state devices use current flow and negative/positive electron charges to achieve their magic. Although Mr. Spock may find the physics of how this technology actually works “fascinating,” it’s more important for you to know the following points regarding solid-state drives, devices, and technology.

Solid-state technology is commonly used in desktop and laptop hard drives, memory cards, cameras, USB thumb drives, and other handheld devices.

SSD form factors are typically 1.8-inch, 2.5-inch, or 3.5-inch.

SSDs can be PATA, SATA, eSATA, SCSI, or USB for desktop systems. Some portable computers