Types of memory in Computer

Types of memory in Computer

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  Types of Memory inComputer
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  Overview • - storageof intermediate data • - necessary to run the computer • - RAM, Cache Primary • - long-term storage of data • - HDD Secondary • - CD, DVD, memory card... Tertiary • - disconnected storage • - unplugged USB flash drive • - external HDD Off-line
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  Primary/Main Memory Main memory is dividedinto two parts : - Random Access memory ( RAM ) should be better known as Read Write Memory - Read Only Memory (ROM) • A set of memory chips, each of them is an integrated circuit (IC) made of millions of transistors and capacitors • Volatile - their state is lost or reset when power is removed from the system. Structure : • Holds data/application programs from input devices or storages Usage : • Determines the number and size of the program can be run at the same time as well as the amount of data that can be processed immediately. Capacity : • processing speed Bus :
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  ROM Retains its datawhen the computer is switched off Holds the bootstrap loader part of the operating system Has contents which are fixed when the chip is manufactured
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  Cache Memory Faster and expensivethan RAM It improves the computer’s performance Processor can use it to store frequently accessed data and program instructions • - L1 : primary cache • (inside the processor) • - L2 : secondary cache • (in the motherboard or near the microprocessor) It is two types :
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  Secondary Storage Storage – anydevices that are capable of holding information, even when the power is off (non-volatile). Ex: Floppy disk drive, hard disk drive, USB flash disk,... Offline storage – type of storage that can be removed and can be accessed from any computers when connected. • Compact Disc (CD) •Capacity: 700 MB •Available from 1982 • DVD •Capacity: 4.7 GB •Available from 1995 • Blu-ray Disc •Capacity: 25 GB •Available from 2006 Optical storage devices • Floppy disk •First available in 1971 •Capacity: 1.44 MB (3 1⁄2-inch floppy disk) • Hard disk drive (HDD) •First introduced in 1956 •Became dominant in the 1960s •Capacity keeps increasing •Max. capacity: 4 TB (as of 2013) Magnetic storage devices • USB Flash drive •Commercially available in 2000 •Max. capacity: 1 TB (as of 2013) •Small size •Ideal solution for storing small data • Solid state drive (SSD) •First introduced in 1995 •Max. capacity: 1 TB (as of 2013) •Very high transferring speed in comparison to normal physical hard disk Flash memory devices
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