16-02-2013, 12:28 PM
Introducing Computer Systems
Computer Systems.doc (Size: 142 KB / Downloads: 15)
What is Computer?
Computer is an advanced electronic device that takes raw data as input from the user and processes these data under the control of set of instructions (called program) and gives the result (output) and saves output for the future use. It can process both numerical and non-numerical (arithmetic and logical) calculations.
(OR)
A Computer is an electronic device that can perform activities that involve Mathematical, logical and graphical manipulations. Generally, the term is used to describe a collection of devices that function together as a system.
Input (Data):
Input is the raw information entered into a computer from the input devices. It is the collection of letters, numbers, images etc.
Process:
Process is the operation of data as per given instruction. It is totally internal process of the computer system.
Output:
Output is the processed data given by computer after data processing. Output is also called as Result. We can save these results in the storage devices for the future use.
Arithmetic Logic Unit (ALU):
The arithmetic and logic unit of CPU is responsible for all arithmetic operations like
addition, subtraction, multiplication and division as well as logical operations, such as less than, equal to and greater than. All calculations and comparisons are performed in arithmetic logic unit.
Control Unit
The control unit is responsible for controlling the transfer of data and instructions among
other units of a computer. It is considered as the “central nervous system” of a computer
as it manages and coordinates all the units of computer. It also performs the physical data transfer between memory and hardware devices.
Registers:
Registers are small high-speed circuits (memory locations). These are used to store data,
instructions and memory addresses (memory location numbers) when ALU performs arithmetic and logical operations. Registers can store one word of data (1 word = 2 bytes and 1 byte = 8 bits) until it is overwritten by another word. Depending on the processor’s capability, the number and type of registers different from one CPU to another. Depending upon their functions, these can be divided into the following six categories:
• General purpose registers • Pointer registers • Segment registers • Index registers
• Flags registers • Instruction pointer registers
IO DEVICES:
MONITORS:
The monitor is the most commonly used output device on most personal computer systems. When you are typing a letter, copying files, or surfing the Internet that are looking at your monitor. They want to sec whether the image is crisp and clear and how well graphics are displayed on the monitor. Two important hardware devices determine the quality of the image you see on any monitor: (1) The monitor (2) The video controller. Color monitors can display between 16 colors and 16 million colors. Today, most new monitors display in color. Many color monitors can be set to work in monochrome or grayscale mode.
The monitors can be divided into to types based on color:
Monochrome monitors display only one color that is black. (Such as green, amber, or white) against a contrasting background. These monitors are used for only displays “text”. where the user does not need to see color graphics.
Grayscale monitors display varying intensities of gray from a very little gray to black against a white or off white background. And these are essentially a type of monochrome monitor. Grayscale flat panel displays are used in low-end portable systems.