Overview of Computers

Two systems of computers:
1) PC – the Personal Computer              
2) Mac – the Apple Macintosh.

Two designs of computers:
1) desktop
2) laptop (notebook)

Computer architecture:  
Main components of a computer            Multimedia devices                  Other peripheral devices

1)  computer                                        1)  CD-ROM / DVD drive         1)  printer            
2)  monitor                                          2)  video card                              2)  scanner  
3)  hard disk/ hard drive                      3)  soundcard                              3) CD-recorder,CD-R/CD- RW  4)  keyboard                                        4)  speakers                                4)  modem      
5)  mouse / trackball /                         5)  headphones / headset             5)  USB flash drive                
    touch pad                                        6)  microphone                             6)  webcam            
                                                                                                                 7)  digital camera
                                                                                                                 8)  digital voice recorder
                                                                                                                 9)  camcorder
Inside the Computer

1) Processor:
The CPU (Central Processing Unit), a complete computation engine that is fabricated on a single chip, is the computer’s brain. It is sometimes referred to as the central processor, microprocessor, or just processor. Two typical components of a CPU are: 1) the arithmetic logic unit (ALU), which performs arithmetic and logical operations, and 2) the control unit, which extracts instructions from memory and decodes and executes them, calling on the ALU when necessary.

2) Memory:
ROM (Read Only Memory) is the computer’s permanent, long-term memory. Tere are types of ROM called PROM that can be altered. The P stands for programmable. ROM's purpose is to store the basic input/output system (BIOS) that controls the start-up, or boot process.
RAM (Random Access Memory) is a working area where the operating system (e.g. Windows), programs and data in current use are kept, ready to be accessed by the processor. It is the best known form of computer memory. However, RAM, unlike ROM, is emptied when the computer is switched off. The more RAM you have, the quicker and more powerful your computer is.
There are two basic types of RAM: dynamic RAM (DRAM) and static RAM (SRAM).
The two types differ in the technology they use to hold data. DRAM, the more common type, needs to be refreshed thousands of times per second. SRAM does not need to be refreshed, which makes it faster, but it is also more expensive than DRAM.

Memory is measure in the following units:
-  1 byte = 8 bits (Each 1 or 0 is called a bit (i.e. binary digit). Each character (i.e. a letter, a number, a space, or a punctuation mark) has its own arrangements of 8 bits, e.g. 01000001 = “A”, 01000010 = “B”.
-  1 KB (kilobyte) = 1024 (210) bytes
-  1 MB (megabyte) = 1024 (210) KB
-  1 GB (gigabyte) = 1024 (210) MB
     
Cache (pronounced as "cash") is a buffer (made of a small number of very fast memory chips) between main memory and the processor. It temporarily stores recently accessed or frequently-used data. Whenever the processor needs to read data, it looks in this cache area first. If it finds the data in the cache, then the processor does not need to do more time-consuming reading of data from the main memory. Memory caching allows data to be accessed more quickly.

Storage Devices
The most common forms of storage devices in a home computer are:
- Hard disk drive
- Floppy disk
- CD-ROM
- CD-R and CD-RW
- DVD-ROM
- USB flash drives

Monitor
There are two types of monitors available for PCs: the traditional CRT (cathode ray tube) and the newer LCD (liquid crystal display). The CRT is used for both televisions and computers. It produces a good quality image at a number of different settings for a reasonable price. LCD monitors, also known as flat panel displays, are used in laptop (or notebook) computers and more frequently for desktops as well. They are lighter and smaller (only inches thick) than CRTs with reduced electromagnetic emissions and power consumption.

Video Card
The card here is a jargon for an electronic circuit board. Video cards are also known as graphics cards, which are responsible for displaying 2D and 3D images on your monitor. 2D graphics are the regular pictures and images that appear on your screen while 3D graphics are mostly used in games and imaging.

Sound Card
A sound card is an electronic circuit board that is mounted inside the computer to control sound output to speakers or headphones, to record sound input from a microphone connected to the computer, and to manipulate sound stored on a disk. Sound cards are essential for multimedia applications and have become common on modern personal computers.
Many sound cards are also Windows-compatible. Many multimedia applications require the system to have a Windows-compatible sound card to run properly.

Ports
A port is an interface on a computer to which you can connect a device. Personal computers have various types of ports. Internally, there are several ports for connecting disk drives, monitors, and keyboards. Externally, personal computers have ports for connecting modems, printers, mice, and other peripheral devices.

There are three common types of external ports that usually come with a computer:

1) Parallel ports (for most printers)
2) Serial ports (for most modems and some mice)
3) USB (Universal Serial Bus) ports (for about every peripheral made in a USB version)

Computer Overviiew

Introduction

The word 'compute' comes from the word 'compute' which means to calculate. So, a computer is normally considered to be calculating device that can speedily perform arithmetic and logical operations.

the original objective for inventing a computer was to create a fast calculating machine, through a major part of work done by computers nowafays is non-mathematical. Therefore, defining a computer assembly only as a calculatinng device is not justified.

The computer is an electronic device designed to accept and store input data, manipulate it and output results under the direction of detailed, step-by-step stored programs and instructions.

Data

It denotes raw facts and figures such as numbers, words, amount, quantity, that can be processed, manipulated or produced by the computer. for example: Rita, 18, XI B. This is raw data.

Information

It is a meaningful and arranged form of data. Raw data does not make any sense on its own. So, it has to be arranged in a meaningful manner such that it makes sense. For example, Information that makes sense can be Rita aged 18 is in class XI B.

Hardware andSoftware

A computer consists of two fundamental components. One is called hardware, the other sothe software. Hardware refers to the physical components or blocks, for example, CPU, memory, input and output devices. Software is the package of instructions designed to operate the conserened hardware, for example, MS-DOS, Microsoft Office, etc. In fact, we can divide software into two broad categories:

1) System Software: It runs the basic functioning of a computer system. It consists of operating systems, compilers, translators, etc.

2) Application Software: the basic aim of making and running a computer is to get work done from it. So, programs which are developed in order to serve a particular application are known as application software. For example, Microsoft Office, Tally, etc.