tailieunhanh - MultiBooks - Tổng hợp IT - PC part 155

Tham khảo tài liệu 'multibooks - tổng hợp it - pc part 155', công nghệ thông tin, kỹ thuật lập trình phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | The fixed head are positioned permanently over certain of the outer tracks there being one head per track so climimating the need for head movement. - The heads are very close disk surface. - Curshion of air carried by the rotating disk. Question 3. Winchester disks hard disks - Comprises a number of platters disks permanently into an airtight enclosure. - All dust is excluded thus perimiting the read write heads to be positioned even closer to the surfaces and so enabling greater recording densities to be employed. - The disks have greater storage capacity and a higher rate of data transger. - It has the lubricated surfaces allowing the heads land when the platters cease to rotate so eliminating head crashes. - Winchester platters are either 14 in 8 in 5 in or 3 in diameter. Question 4. Floppy disks - Diskettes generally called floppy disks are single disks made of flexible plastic and permanently housed is an envelope. - The data on floppy disks is in concentric tracks on the outer part of the surfaces and access to it is via slot in the envelope. - The most common size are 3 in 5 in and 8 in diameter disks the 31A in disks have the advantages of a shutter. - Floppy disks may be either single or double sided and of course the drive needs to be correspondingly equipped. - Both the drives and the floppy disks themselves are inexpensive with the result that they have come into extensive used by small business and home computer buffs. - The range of capacities is from 1 4 to 2 megabytes and transfer rates around 125 to 250 kilobytes per seconds. Question 5. Optical disks - Optical disk are comparatively new development for data storage. - Optical disks consist of a single removable glass plastic or metal disk coated on one side with tellurium and protected by a 1 mm layer or transpacent plastic. - The disk diameters are mostly between 8 in and 14 in they rotate on a spindle in a similar fashion to magnetic disks. - The data is recorded in the form of minute pits .