Computer System Organization

                                                HARDWARE                                       SOFTWARE        

Examples:	CD-ROM, monitor, printer, video card, scanners , label makers, routers , and modems.	Quickbooks, Adobe Acrobat, Winoms-Cs, Internet Explorer ,Microsoft Word , Microsoft Excel
Types:	Input,storage,processing,control, and output devices.	System software, Programming software, and Application software.
Inter dependency:	Hardware starts functioning once software is loaded.	To deliver its set of instructions, Software is installed on hardware.
Function:	Hardware serve as the delivery system for software solutions. The hardware of a computer is infrequently changed, in comparison with software and data, which are “soft” in the sense that they are readily created, modified, or erased on the comput	To perform the specific task you need to complete. Software is generally not needed to for the hardware to perform its basic level tasks such as turning on and reponding to input.
Reliability:	Hardware stays at steady reliability level in useful life.	Software needs constant testing after upgrades.
Failure:	Hardware failure is random. Hardware does have increasing failure at the last stage.	Software failure is systematic. Software does not have an increasing failure rate.
Fault:	Hardware faults is physical.	Software faults are not.
Lifetime:	Hardware wears out over time.	Software does not wear out over time.
Nature:	It is physical in nature	It is logical in nature
Definition:	Devices required to store and execute (or run) the software.	Collection of instructions that enables a user to interact with the computer. Software is a program that enables a computer to perform a specific task, as opposed to the physical components of the system (hardware).
Simple small definition:	Anything which we can see when the computer is off is hardware.	Anything which we can see on the screen when the computer is on is software.

                                                               HARDWARE

     SOFTWARE

Hardware

COMPUTER

MOTHERBOARD

The main circuit board of a microcomputer. the motherboard contains the connectors for attaching additional boards. Typically, the motherboard contains the CPU, BIOS, memory, mass storage interfaces, serial and parallel ports, expansion slots, and all the controllers required to control all the standard peripheral devices, such as the display screen, keyboard, and disk drive; sometimes you will find that the motherboard has other integrated devices such as an audio card and video card. The motherboard is the largest circuit board in most computers and is held by several screws.

CPU

CPU (Central Processing Unit) is the 'brain' that control the internal activities of a computer. Also know as the 'microprocessor', it processes everything from basic instructions to complex functions using its components such as control unit, arithmetic logic unit and register. It is the most expensive part of a computer and the reliability of a computer system is determined by the quality of its processor.

ALU (Arithmetic Logic Unit) - This unit performs the computing functions involving integers (whole numbers).

   # Arithmetic operations which include addition, subtraction, multiplication     and division.

   # All logic operations which involve comparisons such as less than, greater than, or equal to.

All information in a CPU is reduced to a numeric function; therefore, the ALU is constantly handling arithmetic and logic operations.

The results of these operations are stored in the registers or in memory or sent to output devices.

Registers - All data is temporarily stored in registers during the execution of programs and the size of the internal register determines how much information the CPU can process at one time.

Control Unit - This unit handles the timing and control signals to all the operations in the system. You can compare the control unit to a police officer directing traffic at a busy intersection; but, instead of directing cars, the control unit directs data flow between the computer processor, memory and peripherals.

Input - This is the process by which external data is received into the computer. This could either be running a program or getting keyboard responses. Common inputs include a keyboard, mouse, modem, scanner, etc. The computer system analyzes the input data.

Output - Output is the process by which the CPU sends data to devices such as the monitor, printer, disk drive, etc. Output takes the results of the processing and sends them to be stored in memory or printed or displayed. Output is the final result of the processing of the data that was input and used by the computer system.

Data must be stored either temporarily or permanently. Therefore, this is where memory is required. The computer needs a way to hold onto data as the processing is being performed.

Memory - The computer stores data in memory and retrieves the data it needs from memory. There are two kinds of memory - ROM and RAM.

ROM (Read-Only Memory) is permanent and will be retained even when the computer is turned off - eg. BIOS.

RAM (Random Access Memory) is volatile and data stored in RAM will be erased when the computer is turned off. The processor uses RAM to store data and retrieves data from RAM as it's needed. The instructions of a program, for example, would be stored in RAM. RAM will be lost if the computer loses power.

RAM (PRIMARY STORAGE)

RAM (random access memory) is the place in a computer where the operating system, application programs, and data in current use are kept so that they can be quickly reached by the computer's processor. RAM is much faster to read from and write to than the other kinds of storage in a computer, the hard disk, floppy disk, and CD-ROM. However, the data in RAM stays there only as long as your computer is running. When you turn the computer off, RAM loses its data. When you turn your computer on again, your operating system and other files are once again loaded into RAM, usually from your hard disk.

SECONDARY STORAGE

Secondary storage is commonly referred to as hard disk. It is a non-volatile storage and is capable of storing large amounts of data. As secondary storage is non-volatile, it is used for safe or offline storage of data and all the data can be stored permanently.

INPUT DEVICE

Keyboard

Mouse

Joystick

Scanner

Light pen

Voice recorder

Graphic tablet

Webcam

OUTPUT DEVICE

Monitor 

Speaker

Printer

Plotter

Projector