DIDI JUARDI, M.Kom

Computer System

People

Software

Hardware

People

• Computer programmer – person who writes programs

• Users or End-users – make use of the computer’s capabilities

Software

• Programs

• Set of instructions that directs the hardware to do a required task and produce the desired results

Hardware:Basic Components of a Computer

Computer Components1. Input Devices

- examples: keyboard and the mouse- data entered on the keyboard and temporarily

stored in the computer’s memory and displayed on the

monitor

2. System Unit- contains the electronic circuits that cause the

processing of data to occur- consists of central processing unit, memory,

(RAM and ROM) and other electronic components

- CPU has a control unit and arithmetic/logic unit- RAM temporarily stores data and program

instructions when they are processed

4. Output Devices- most commonly used output devices are monitor and printer - Monitor :commonly as CRT or Flat Panel Display- Printer: Dot-Matrix, Ink-Jet etc.

5. Secondary Storage Devices- also known as auxiliary storage devices- stores instructions and data when they are not being used by the system unit- Examples : floppy disk and hard disk drive

Computer Components – cont.

Input Process Output

DataInformation

Storage

How a Computer System Works

How a Computer System Works – cont.

Software- The instructions needed to direct the computer to

complete specific tasks.

• The CPU follows the step-by-step instructions in a program to complete the tasks from user.

• Operating system is the system software that controls the basic, low-level hardware operations and file management.

Microcomputers- Also known as personal computers- Physical sizes : palmtop, desktop and tower case- Cheaper and smaller in size

Minicomputer- Also known as departmental computers- Physical sizes : small to large cabinets- Support business application

Computer Configuration and Classification

Mainframe- Large computers with the capability to process data at millions of instructions per second.

- Physical size : partial to full room of equipment

Supercomputer- Most powerful and expensive computers

- Vast quantities of data manipulation - Physical size : full room of equipment- No. of users : hundreds of users

Computer Configuration and Classification – cont.

Central Processing Unit (CPU)

- It is the heart of the computer, that is the microprocessor chip.

- A highly complex, extensive set of electronic circuitry that executes stored program instructions.

- CPU perform three main tasks :-• Perform arithmetic operations• Perform logic operations• Retrieval and storage of data

- CPU consists of two main units :-1. Arithmetic Logic Unit (ALU)

- arithmetic operations e.g. +, -, x, /- logic operations e.g. >, >=, ==, <, <=

CPU – cont.

2. Control unit - fetches instructions from memory- decode/translate instructions- executes the processing tasks - stores result in memory

CPU – cont.

- CU fetches instructions from memory - CU decodes/translates instructions, directs necessary data to ALU

- ALU executes arithmetic/logic instruction-ALU stores results into memory

What happens in a CPU?

Memory - also known as primary storage, primary

memory, main storage, internal storage, and main memory

- Consists of RAM and ROM 1. RAM (Random Access Memory)

- volatile; means the data exists only when power is ON - two types of RAM, dynamic and static

2. ROM (Read Only Memory) - non-volatile; means data permanently stored in and cannot be changed

CPU – cont.

Function of Computer System

Data handling

I InputP ProcessO OutputS Storage

Processing: Batch vs. Interactive

• 2 types of information processing– Batch processing– Interactive processing : Real time

Input devices

• Accept data or commands and convert them to electronic form

• Getting data into the computer– Typing on a keyboard– Pointing with a mouse– Scanning with a wand reader or bar-code

reader– Terminal

Output devices

Monitor or screen• Text• Numbers• Symbols• Art• Photographs• Video

Printer• Black and white• Color

• Convert from electronic form to some other form

• May display the processed results• Usable information

Input and Output Devices

1. Input devices

- Common type of devices used are the keyboard and the mouse- Standard type of keyboard is the QWERTY which has 86 keys (basic) and 101-102 keys (enhanced).- Mouse is a pointing device for effective use of computer interface. Trackball and touch pad are also considered as pointing devices.

Input and Output Devices – cont.

Digitizer- A pad with a pen-like stylus. - The tablet sends electronic signals to the computer, displaying the image drawn.

Input and Output Devices – cont.

the use of special equipment to collect data at the source and send it directly to the computer.

Source data automation

MICR Images OCR

Bar code Hand Written

Input devices– cont.

Input and Output Devices – cont.

2. Output devices- most common devices are monitor displays

and printers- Two types of display; flat panel display

and CRT display (Cathode Ray Tube)- Two categories of printers; impact and

non-impact printers

Displays

1. Flat Panel- commonly used in laptop, notebook- examples of flat panel; LCD, Gas

Plasma

2. CRT- produce best images for computers- two types of display; monochrome and

color- monochrome; displays one color (green

or amber)- color; four types:

Input and Output Devices – cont.

Standard Graphic Add-on-Boards

Resolution (by pixels)

CGA (Color Graphic Adapter) 640 x 200EGA (Enhanced Graphic Adapter) 640 x 350VGA (Video Graphic Array) 640 x 480SVGA (Super Video Graphic Array) 1024 x 768

Displays – cont.

Input and Output Devices – cont.

Two types of printers (according to printing methods)

Impact printers -use a physical contact with the paper to produce an image-e.g. dot matrix printer and line printer

Non-impact printers-Place images on a paper without physically touching it-e.g. thermal, inkjet, laser printer

Input and Output Devices – cont.

Printers

Can you think of any other input/output devices?

The Processor

Central Processing Unit (CPU)

• Converts data to useful information

• Interpret and execute instructions

• Communicate with input, output and storage

Two Types of Storage

• Secondary storagelong-term storage

• Primary storage or memorytemporary storage

Memory / Primary Storage

• Temporary storage

• Holds input to be processed

• Holds results of processing

• Contains the programs to control the computer and manipulate input into output

• Volatile

Secondary Storage

• Long-term storage• Non-volatile

Secondary Storage Examples• Magnetic disks – read and written by

magnetic disk drive– Hard disk– Diskette

• Optical disks – read and written by optical disk drives– CD-ROM– DVD-ROM

• Magnetic tape – read and written by magnetic tape drives– Primarily used for back-up

Magnetic Disk

• It is needed because – Main memory stores data temporarily– Main memory space is limited

Secondary Storage

Benefits of secondary storage Space Reliability Convenience Economic