cs240 Exam 2 Review Sheet

cs240 Exam 2 Review Sheet - Chapter 10 Peripherals All...

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Chapter 10 – Peripherals All items mentioned except for CPU, memory, and power supply are considered peripheral (external) to the main processing function of the computer. Some use USB, parallel, serial ports, or their own interface to the internal system buses that connect parts of the computer (PCI Bus). Secondary Storage Hierarchy of Storage: CPU Registers → Cache → DRAM → Flash Memory → Magnetic Disk → Optical Disk Conventional and cache memory are known as primary memory. As storage capacity increases, so does access time. Secondary Storage is storage not immediately available to the CPU. Types of storage: Solid State Memory – flash memory is nonvolatile electronic integrated circuit memory. Similar to ROM, but allows small blocks/bytes to read, write, erased. Read access is quite fast. Flash memory must be erased in blocks so that write accesses require an additional step that rewrites the unchanged data back to the block. Erase and rewrite operation is very slow. Optical Disk Storage – write-once and read/write forms. Conceptually CD-Rom is similar to magnetic disk: data is stored in blocks on the disk, blocks can be arranged in files with a directory structure similar to that of magnetic disks. Data on a CD- Rom is stored on a single track which spirals from the inside of the disk to the outside. This design was originally for Audio (sequential access throughout). The CD is read at Constant Linear Velocity (CLV). Typical CD stores 270K blocks of data each 2352 bytes, with 2048 bytes of data, 16 Byte headers which provides 12 bytes to locate the start of a block and 4 bytes for block ID. Data is stored on the disk in the form of pits and lands that are burned into the surface of the disk using a laser. The translation of small frames is performed by the CD-Rom device hardware and is invisible to the computer. DVDs are similar, but the laser uses a shorter light wavelength (visible red instead of infrared) which allows tighter packing of bits onto the disk. Also, the disk can be focused so that two layers of data can be placed on the same disk underneath the other. Each layer of a DVD can hold 4.7GB, both layers on both sides = 17GB. WORM (write once read many times) provides high capacity storage, compact size, low cost and removability. WORM works similar to CD/DVD but the material of the disk is different, and is instead blistered by a laser across the surface which corresponds to the pits found in a normal CD/DVD. Magnetic Disks – consists of one or more flat circular platters coated with magnetic substance which can be polarized in 2 directions (0 1). Hard disk drives contain several platters mounted on the same axis with heads on each surface of each platter. Structure Follows:
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This note was uploaded on 11/06/2011 for the course CS 240 taught by Professor Wong during the Fall '10 term at Bentley.

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cs240 Exam 2 Review Sheet - Chapter 10 Peripherals All...

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