Memory

MEMORY

·        It is used to store data and instruction for future used.

·        When the user is entering the data and instruction to the computer system then the computer is first store this enter data in to the computer memory.

·        After processing the generate result is store in the memory and then transfer in to the output devices for showing result.

·         Generally, the memory is classified in to two types (1) Primary Memory (2) Secondary Memory

Primary Memory:

RAM (Random Access Memory):

·        it is stands for Random Access Memory.

·        It is also called as Read and write only memory.

·        It is consisting of black plastic integrated micro chip and row of pins on each side.

·        It is a volatile or temporary memory because the information on the RAM are not permanent.

·        The contains of the RAM are save until the computer system is switch on but the computer is switch off then the contains of the RAM are lost.

·        It stores the next execute or currently execute data by the processor.

·        The speed of the RAM is 80 Nano second.

·        The RAM are grouped in two types 1. SIMM, 2. DIMM.

·        The size of RAM varies from 128 MB to 8 GB or more.

Types of RAM

(1) S-RAM        (2) D-RAM

S-RAM- (Static RAM)

·        It is stands for Static RAM.

·        The information on S-RAM present or save until the computer system is switch on but the computer is switch off then the information on S-RAM are lost.

·        It is more expensive and consume more power.

·        It speed is very high.

D-RAM- (Dynamic RAM)

·        It is stands for Dynamic RAM.

·        In a D-RAM the information is refreshed at a particular time of interval and the new information will be loaded in to the D-RAM memory.

·        It is less expensive and consume low power.

·        Its speed is very slow.

ROM- (Read Only Memory)

·        It stands for Read Only Memory.

·        It is a permanent type of memory.

·        When power supply is switch off its contents are not lost.

·        The user cannot write in to a ROM its contents are written in to at manufacturing.

·        Its store permanent programs and other type of data which are needed by the computer execute user programs.

Types of ROM:

1.     P-ROM- Programmable Read Only memory (Wen Tsing Chow 1956)

2.     EP-ROM- Erasable Programmable Read Only Memory

·        The store data is EP-ROM can be erased by exposing them to high intensity short wave ultraviolet light for about 20 minute.

·        When an EP-ROM is exposed to ultraviolet light the entire data is erased.

·        EP-ROM are cheap, reliable and hence they are widely used. They can store programs which are permanent but need updating.

·        UVEP-ROM- Ultraviolet PROM (1971 DOV Frohman [intel Company])

Secondary Memory:

·        It is used to store data and information for a long period of time.

·        It is not directly communicating with CPU processor. First the data and information copied in to the primary memory (RAM) and then it transfers to the processor for processing.

·        It is a non-volatile or permanent type of memory.