Friday, April 1, 2011

SYSTEM CONCEPT

Define computer system

A Computer System is defined as combination of component designed to process data and store files.


Meaning of input, process,output and storage
1. INPUT 
                  Any data and instructions entered into the memory of a computer. There are 
                  four types of input which are: text, graphics, audio and video.
Example of devices:
Keyboard, mouse, digital camera, joystick, trackball, touch screen, microphone, pointing stick, graphic tablet and scanner, barcode reader.

2. PROCESS
CPU or Central Processing Unit/ Processor/ Microprocessor is an electronic component on a computer’s motherboard that interprets and carries out the basic instructions that operate the computer.
Example of devices:
Intel® Core™2 Duo Processor, AMD Athlon, G4, Mac

3. OUTPUT 
The result of raw input data that has been processed by the Central Processing Unit (CPU) into meaningful information.
Example of devices:
Speaker, monitor, LCD projector, printer and plotter




4. STORAGE 
                  A location in which data, instructions, and information are saved for future
                  use.
Example of devices:


                  CDROM, diskette, hard disk, flash disk.


Describe the information processing cycle which includes ipnut,process, output and storage


Information processing cycle of computer can be well described by the following points:
(1) input, (2) processing, (3) output and (4) storage

  1. Input-entering data into the computer.
  2. Processing-performing operations on the data.
  3. Output-presenting the results.
User will input the data to be processed by the processor.
The storage holds databases, files & programs. The output devices present the processed data as useful information products for the user.

Blog diagram of the information processing cycle















MACHINE CYCLE
Basic operation called Machine Cycle
FETCHING : the process of obtaining a program instruction or data item from memory
DECODING : the process of translating a program instruction into signal that the
computer can execute
EXECUTING : the process of implementing the instructions in a program
STORING : the process of writing the result to the storage or memory

Fetching-Mengambil - proses mendapatkan arahan program atau item data dari memori/ingatan
Decoding- proses menterjemah arahan pogram menjadi isyarat untuk dilaksanakan komputer
Executing-Pelaksanaan -Proses pelaksanaan arahan di dalam sebuah program
Storing-Menyimpan - proses penulisan hasil untuk simpanan atau memori

Data presentation

BINARY DIGIT


Computers recognize only two discrete states: on and off. These states can be represented by two digits, 0 and 1. Each 0 or 1 is called a bit in the binary system.


Bit is the smallest unit of data a computer can process. Bit is a short for binary digit. The binary system has a base of 2 with the two digits (0 and 1). Combinations of 0s and 1s represent larger numbers.


BIT

A bit is the smallest unit of data that the computer can process. Bit is a short for binary digit. A bit is represented by the numbers 1 and 0. These numbers represent the binary system. They correspond to the states of on and off, true and false, or yes and no.
All digital data use the binary system to process the information. This information include letters, digits or special character.

BYTE

Byte is a unit of information built from bits. One byte is equals to 8 bits. Eight bits that are grouped together as a unit. A byte provides enough different combinations of 0s and 1s to represent 256 individual characters.
One byte represents a single character such as the number 3, letter b 
or a $ symbol. Bits and bytes are the basis for representing all meaningful information and programs on computers.

CHARACTER



8 bits = 1 byte

One byte represents one character such as A, 7, 9 and +.Eight bits that are grouped together as a unit. A byte provides enough different combinations of 0s and 1s to represent 256 individual characters.



For example, the capital letter F is represented by the binary code 01000110 that can be understood by the computer system. Eight bits grouped together as a unit are called a byte. A byte represents a single character in the 
computer.



CHARACTER CODES



There are three character codes to represent characters which are ASCII, EBCDIC and Unicode. Each byte contains eight bits. A byte provides enough 
different combination of 0s and 1s to represent 256 characters.
The combinations of 0s and 1s are defined by patterns. These patterns are called coding scheme. The 256-character capability of ASCII and EBCDIC is too small to handle the characters that are used by other languages such as
Arabic, Japanese and Chinese.



The Unicode coding scheme is designed to solve this problem. It uses two bytes (16 bits) to represent one character. Unicode will have more than 65,000 different characters. This can cover all the world’s languages.

Introduction to BINARY CODING

WHAT IS ASCII?
ASCII pronounced as "ask-key" stands for the American Standard Code for Information Interchange and was proposed by ASA (American Standard Association) in 963 and was finalised in 1968.ASCII is a standard of 7-bit code used to represent characters, which include letters, numbers and punctuation marks.7 bits allow the computer to encode a total of 128 characters for the numbers 0-9, uppercase and lowercase letters A-Z and a few punctuation symbols. However this 128 bit code only suitable for english language speaking users.IBM and Apple expanded the amount of space reserved for the character codes to 8-bits, equivalent to 1 byte.

FUNCTIONS OF ASCII

ASCII was established to achieve compatibility between various types of data processing equipment making it possible for the components to communicate with each other successfully.ASCII enables manufacturers to produce components that are assured to operate correctly in a computer.ASCII makes it possible for humans to interact with a computer. It also enables users to purchase components that are compatible with their computer configurations

HOW ASCII WORKS IN A COMPUTER SYSTEM?

When you press a key, for example the letter D on your keyboard, the electronic signal is sent to the CPU for the computer to process and store in memory. Every character is converted to its corresponding binary form. The computer the processes the letter as a byte., which actually a series of on and off of electrical states. When the computer is finished processing the byte, the software installed in the system convert the byte back which is then displayed in the screen. In this example, the letter D is converted to 01000100.

State the unit of data measurement

1
Bit
Single Binary Digit (1 or 0)
2
Byte
1 Byte = 8 bits
3
Kilobyte (KB)
1 KB = 1024 bytes or 1 KB = 10 bytes
4
Megabyte
1 MB = 1 048 576 bytes or 1 MB = 20bytes
1 MB = 1024 KB
5
Gigabyte
1 GB = 1 073 741 824 bytes or 1 GB = 230 bytes
6
Terabyte (TB)
1 TB = 1 099 511 627 776 bytes or 1 TB =40 bytes




State the units of clock speed measurement

When we hear about a computer’s ‘speed’, they mean how fast it can
process data. In other words, this means the speed that the computer can
turn data into information.
Every microprocessor contains a system clock. The system clock controls the speed of
all the operations within a computer.The speed of the clock in measured by how many
cycles per second the clock makes.

MEGAHERTZ (MHz)
Mega is prefix that stands for million. Example àone computer that operates at 933 MHz
has 933 million clock cycles in one second.

GIGAHERTZ (GHz)
Giga is prefix that stands for billion 1 GHz equal to one billion cycles of the system clock
For example, a microprocessor that runs at 200 GHz executes 200 billion cycles per
second. This is what they a talking about if they say a computer is a 2.4 GHz machine.
Its clock rate is 2.4 billion cycles per second.In relation with megahertz, 1.0 GHz is 
equivalent to 1000 MHz. GHz is most often used as a measurement of a pc processor
chip & power, with bigger numbers meaning more speed and higher price

Hertz & Second
The clock speed unit is measured in hertz.
1 Hertz =121 cycle1 second"> 1 cycle / 1 se

1 Megahertz (MHz) = 1,000,000 cycles / 1 second 121,000,000 cycles1 second">
1 GHz = 1,000,000,000 cycles / 1 second 121,000,000,000 cycles1 second">
1 GHz = 1 000 MHz

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