A computer is a programmable machine that receives input, store and process data automatically, and provides an output in a useful format.
Modern computers based on integrated circuits are millions to billions of times more likely than the first machines, and occupy a fraction of the space . simple computers are small enough to fit in mobile devices, and can be powered by a small battery. Personal computers in their various forms are icons of the Information Age and are what most people think "computers". However, computers embedded in many devices MP3 players combat aircraft and toys to industrial robots are the most numerous.
BLOCK DIAGRAM OF COMPUTER
BLOCK DIAGRAM OF A PC
A computer can process data, images, sounds and graphics. They can solve complex problems quickly and accurately.
Input Unit:
Computers need to receive data and instructions to solve any problem. That is why we need to enter data and instructions in computers. The input unit consists of one or more input devices. Keyboard is one of input devices commonly used. Other input devices commonly used are mouse, floppy, tape, etc. All input devices perform the following functions. # Accept the data and instructions from the outside world. # The conversion into a form that the computer can understand. # Provide the converted data to the computer system for further processing.
Storage unit:
The storage unit of the computer contains data and instructions that are entered by the input unit before they are processed. It retains the interim and final results before they are sent to output devices. It also logs data for later use. The various storage devices of a computer system are divided into two categories.
1. Storage Capacity: Stores and provides very fast. This memory is typically used to maintain the current program being executed in the computer, data received from the input unit, the intermediate and final results of the program. The primary memory is temporary. Data is lost when the computer is off. To store data permanently, the data must be transferred to secondary storage. The cost of primary storage is more compared to secondary storage. This is why most computers have a limited capacity primary storage.
2. Secondary storage: Secondary storage is used as an archive. It stores multiple programs, documents, databases, etc. The programs you run on your computer are first transferred into the primary memory before it is actually executed. Whenever the results are recorded, in addition, they are stored in secondary memory. The secondary storage is slower and less expensive than the primary memory. Some of these devices are commonly used secondary storage hard disk, CD, etc.
Memory Size:
All digital computers use the binary system, 0 and 1. Each character or number is represented by an 8-bit code. The set of 8 bits is called a byte. A character occupies 1 byte of space. A digital space occupies 2 bytes. Byte is the space in memory.
The size of primary storage is specified in KB (kilobytes) or MB (megabytes). A KB is 1024 bytes and MB is equal to 1000KB. The size of primary storage in a typical PC usually starts at 16MB. PC with 32 MB, 48 MB, 128 MB, 256 MB of memory are quite common.
Output unit:
The output unit of a computer provides the information and results of a calculation to the outside world. Printers, Visual Display Unit (VTE) are commonly used output devices. Other output devices commonly used are the floppy drive, hard disk, and tape player.
Arithmetic Logic Unit:
All calculations are performed in the Arithmetic Logic Unit (ALU) of the computer. Comparison and it makes the decision. The ALU can perform basic operations such as addition, subtraction, multiplication, division, etc. and not the logic operations ie,>, <, =, "etc. When the calculations are required, the control unit transmits the data storage unit ALU Once the calculations are performed, the results are transferred to the storage unit by the control unit and is then sent to the output unit for displaying results .
Control unit:
It controls all other units of the computer. The controller tells the input device, which store data after its receipt of the user. It controls the flow of data and instructions from the storage unit ALU. It also controls the flow of results from the ALU to the storage unit. The control unit is usually designated as the central nervous system of the computer that controls and synchronizes their work.
CPU:
The ALU control unit and the computer are together known as the central processing unit (CPU). The CPU is like the brain performs the following functions: • It performs all calculations. • It takes all the decisions. • It controls all units of the computer. A PC can be CPU-IC as Intel 8088, 80286, 80386, 80486, Celeron, Pentium, Pentium Pro, Pentium II, Pentium III, Pentium IV, Dual Core and AMD etc.