Form Factors
| The cornerstone of the PC industry has always been standardization. With disk drives, this is evident in the physical and electrical form factors that comprise modern drives. By using industry-standard form factors, you can purchase a system or chassis from one manufacturer and yet physically and electrically install a drive from a different manufacturer. Form factor standards ensure that available drives will fit in the bay, the screw holes will line up, and the standard cables and connections will plug in. Without these industry standards, there would be no compatibility between different chassis, motherboards, cables, and drives. You might wonder how these form factors are established. In some cases, it is simply that one manufacturer makes a popular product of a particular shape and connection protocol and others copy or clone those parameters, making other products that are physically and/or electrically compatible. In other cases, various committees or groups have been formed to dictate certain industry standards. Then it is up to the companies that make applicable products to create them to conform to these standards. Over the years, disk drives have been introduced in several industry-standard form factors, usually identified by the approximate size of the platters contained inside the drive. Table 9.1 lists the various disk drive form factors that have been used in PCs and portables.
Currently, 3 1/2" drives are the most popular for desktop, whereas 2 1/2" and smaller drives are popular in laptops and other portable devices. Parallel ATA 3 1/2" drives are quickly being phased out to be replaced by Serial ATA drives, which are now the most commonplace drive interfaces in new desktop systems. Notebooks, meanwhile, are just beginning to transition toward 2 1/2" drives featuring the Serial ATA interface. Part of the reason most laptop systems continue to support Parallel ATA is that, until recently, the motherboard chipsets supported only Parallel ATA natively and adding an extra chip for SATA support was cost-, space-, and power-prohibitive. Not to mention that there were originally no SATA 2 1/2" drives on the market. But that is changing. The 900 series chipsets from Intel that are found in newer systems include native SATA support, and SATA 2 1/2" drives are now available as well. 5 1/4" DriveShugart Associates first introduced the 5 1/4" form factor along with the first 5 1/4" floppy drive in 1976. The story goes that founder Al Shugart then left that company and founded Seagate Technologies, which introduced the first 5 1/4" (Model ST-506, 5MB capacity) hard disk in 1980, predating the IBM PC. IBM later used the Seagate ST-412 (10MB) drive in some of its PC-XT models, which were among the first PCs to be sold with hard drives built in. The physical format of the 5 1/4" hard disk back then was the same as the 5 1/4" full-height floppy drive, so both fit the same size bay in a chassis. For example, the original IBM PC and XT models had two 5 1/4" full-height bays that could accept these drives. The first portable systems (such as the original Compaq Portable) used these drives as well. Later, the 5 1/4" form factor was reduced in height by one-half when the appropriately named 5 1/4" half-height floppy drives and hard drives were introduced. This allowed two drives to fit in a bay originally designed for one. The 5 1/4" half-height form factor is still used as the form factor for modern desktop CD-ROM and DVD drives and is the standard form factor for larger drive bays in all modern desktop PC chassis. Early portable PCs, such as the IBM Portable PC, used this form factor as well. 3 1/2" DriveSony introduced the first 3 1/2" floppy drive in 1981, which used a smaller width and depth but the same height as the half-height 5 1/4" form factor. These were called 3 1/2" half-height drives, even though there was no such thing as a "full-height" 3 1/2" drive. Rodime followed with the first 3 1/2" half-height hard disk in 1983. Later 3 1/2" floppy and hard drives would be reduced in height to only 1", which was just under one-third of the original 5 1/4" full-height form factor (these were sometimes called 1/3-height drives). Today, the 1" high version has become the modern industry-standard 3 1/2" form factor. 2 1/2" DrivePrairieTek introduced the 2 1/2" form factor in 1988, which proved to be ideal for laptop and notebook computers. As laptop sales grew, so did sales of the 2 1/2" drives. Although PrairieTek was the first with that form factor, other drive manufacturers quickly capitalized on the market by also introducing 2 1/2" drives. Finally, in 1994 Conner Peripherals, Inc., paid $18 million for PrairieTek's 2 1/2" disk drive technology and PrairieTek went out of business. Since the 2 1/2" drives first appeared, virtually all laptop and notebook systems have used them. Although 2 1/2" drives can also be used in desktop systems, the 3 1/2" drive continues to dominate the desktop market due to greater capacity and speed and lower cost. The 2 1/2" drives have been manufactured in various thicknesses (or heights), and many notebook or laptop systems are restricted as to how thick a drive they can support. Here are the common thicknesses that have been available:
By far, the most popular sizes are 9.5mm and 12.5mm, which are the sizes used by most laptop and notebook systems. Currently, most drive manufacturers are concentrating on the 9.5mm form factor. A thinner drive can almost always be installed in place of a thicker one; however, most systems do not have the room to accept a thicker drive than they were originally designed to use. 1.8" DriveThe 1.8" drive was first introduced by Integral Peripherals in 1991 and has had problems gaining acceptance in the marketplace ever since. This size was initially created because it fit perfectly in the PC Card (PCMCIA) form factor, making it ideal as add-on removable storage for laptop and notebook systems. Unfortunately, the 1.8" drive market has been slow to take shape, and in 1998 an investment group called Mobile Storage bought Integral Peripherals' 1.8" drive technology for $5.5 million; Integral Peripherals then went out of business. Several other companies have introduced 1.8" drives over the yearsmost notably HP, Calluna, Toshiba, and Hitachi. Of those, only Toshiba and Hitachi continue to manufacture drives in that format. HP exited the disk drive market completely in 1996, and Calluna finally ceased operation in 2001. Toshiba introduced its 1.8" drives (available in the physical format of a Type II PC-Card) in 2000, and Hitachi entered the 1.8" drive market in 2003. The 1.8" drives are available in capacities of up to 60GB or more and, depending on the model, can be used anywhere a standard PC Card can be plugged in. 1" DrivesDuring 1998, IBM introduced a 1" drive called the MicroDrive, incorporating a single platter about the size of a quarter! Current versions of the MicroDrive can store up to 4GB or more. These drives are in the physical and electrical format of a Type II Compact Flash (CF) card, which means they can be used in almost any device that takes CF cards, including digital cameras, personal digital assistants (PDAs), and MP3 players. IBM's disk drive division was sold to Hitachi in 2003 and combined with Hitachi's storage technology business as Hitachi Global Storage Technologies. Note HP introduced a 20MB 1.3" disk drive called the KittyHawk in 1992, originally intended for the handheld computer market. In 1994, HP followed with a 40MB model. These small drives were expensive and proved to be too far ahead of their time, as were the handheld computers they were intended for. After two years of low sales, HP discontinued the KittyHawk family. In 2004, Toshiba introduced the smallest drive to date: the 0.85" drive, which is about the size of a postage stamp and stores up to 4GB. This drive is not really designed for PCs but will be used in cell phones, digital audio players, PDAs, digital still cameras, camcorders, and more. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
EAN: 2147483647
Pages: 283
- Chapter II Information Search on the Internet: A Causal Model
- Chapter III Two Models of Online Patronage: Why Do Consumers Shop on the Internet?
- Chapter IX Extrinsic Plus Intrinsic Human Factors Influencing the Web Usage
- Chapter XIII Shopping Agent Web Sites: A Comparative Shopping Environment
- Chapter XV Customer Trust in Online Commerce