Download - DIDI JUARDI, M.Kom
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