The Computer System-Computer Memory Overview

Computer Memory Overview

The computer memory is one of the most important elements in a computer system. It stores data and instructions required during the processing of data and output results. Storage may be required for a limited period of time, instantly or for an extended period of time.

Types of Memory:

In general, the memory is classified into two categories.

• Primary memory or Main memory.
• Secondary memory or Auxiliary memory.

Main Memory:

The main memory in a computer is called Random Access Memory. It is also known as RAM. This is the part of the computer that stores operating system software, software applications and other information for the central processing unit (CPU) to have fast and direct access when needed to perform tasks.

    Primary memory further classified in two categories:

1. Random Access Memory (RAM):

• Random Access Memory (or simply RAM) is the memory or information storage in a computer that is used to store running programs and data for the programs. Data (information) in the RAMcan be read and written quickly in any order. Normally, the random access memory is in the form of computer chips.
• There are two categories of RAM:
• 1.SRAM
• 2.DRAM

1.SRAM:SRAM (static RAM) is random access memory (RAM) that retains data bits in its memory as long as power is being supplied. Unlike dynamic RAM (DRAM), which stores bits in cells consisting of a capacitor and a transistor, SRAM does not have to be periodically refreshed.

DRAM:

• A type of physical memory used in most personal computers. The term dynamic indicates that the memory must be constantly refreshed (reenergized) or it will lose its contents. RAM(random-access memory) is sometimes referred to as DRAM (pronounced dee-ram) to distinguish it from static RAM(SRAM).

Secondary Memory (Auxiliary Memory/Storage Devices)

2.Secondary Memory (Auxiliary Memory/Storage Devices)

• Secondary memory(or secondary storage) is the slowest and cheapest form of memory. It cannot be processed directly by the CPU. It must first be copied into primary storage(also known as RAM).
• Secondary memory devices include.
  Magnetic Disks :
• Hard Disk Drive.
• Floppy Disk.
• Memory Stick.
• Optical Disk:

CD,DVD, Blue-ray Disk

• Solid State Disks:

Pen/Flash Drive

Cache Memory

Cache Memory:

• Cache memory is a storage buffer that stores the data that is used more often. temporarily and makes them available to CPU at a fast rate.
• The data and instructions that are required during the processing of data are brought from the secondary storage devices and stored in the RAM. For processing it is required that the data and instructions are accessed from the RAM and stored in the registers.
• Cache memory is a very high speed memory placed in between RAM and CPU. Cache memory increases the speed of processing.
• Cache memory is very expensive, so it is smaller in size. Generally. computers have cache memory of sizes 256 KB to 2 MB.

Input and output

Input and output:

Direct memory access (DMA) is a method that allows an input/output (I/O) device to send or receive data directly to or from the main memory, bypassing the CPU to speed up memory operations. The process is managed by a chip known as a DMA controller (DMAC).

External device 

 

External device :

• external device– Computer Definition. Any peripheral devicethat is not housed inside the computer cabinet. Monitors, keyboards, mice and printers are inherently external devices; however,drives, network adapters and modems may also be external. Seeexternal drive, external modem and USB adapter.

External interface

external interface –  (1) A connection to a device outside the computer’s cabinet. Contrast with internal interface.

(2) A connection to the WAN side of a router.(wide- area –network).

operating system overview

operating system overview :

• Operating System – Overview. … An operating system is a software which performs all the basic tasks like file management, memory management, process management, handling input and output, and controlling peripheral devices such as disk drives and printers.
• Operating system performs the following functions:
• Booting: Booting is a process of starting the computer operating system starts the computer to work. …
• Memory Management.
• Loading and Execution.
• Data security.
• Disk Management.
• Process Management.
• Device Controlling.
• Printing controlling.

 

Memory Management& Loading and Execution:

Memory Management:

• Memory managementis the functionality of an operating system which handles or manages primary memoryand moves processes back and forth between main memory and disk during execution. Memory management keeps track of each and every memory location, regardless of either it is allocated to some process or it is free.

Loading and Execution:

• A loader is a major component of an operating system that ensures all necessary programs and libraries are loaded, which is essential during the startup phase of running a program. It places the libraries and programs into the main memory in order to prepare them for execution.

Data security& Disk Management:

Data security:

• Data security refers to the process of protecting data from unauthorized access and data corruption throughout its lifecycle. Data security includes data encryption, tokenization, and key management practices that protect data across all applications and platforms.

Disk Management:

• Disk Management is a Microsoft Windows utility first introduced in Windows XP as a replacement for the fdisk command. It enables users to view and manage the disk drives installed in their computer and the partitions associated with those drives.

 

Process Management& Device Controlling

Process Management:

 

• Process managementis an integral part of any modern-day operating system (OS). The OS must allocate resources to processes, enable processesto share and exchange information, protect the resources of each process from otherprocesses and enable synchronization among processes.

Device Controlling:

• A controlsystem manages, commands, directs, or regulates the behavior of other devicesor systems using control loops. It can range from a single home heating controller using a thermostat controlling a domestic boiler to large Industrial control systems which are used for controlling processes or machines.

Printing controlling

• Printedcircuit board (PCB), sometimes with its own CPU, that translates a computer or software’s output (print) commands into the signals that a print engine can use to print a page.