Architecture and components of computer systems. Use of computer systems.Data representation in computer systems

What is Computer Hardware? You are already aware that a computer system is made up of several different components. Those that can be seen and touched are referred to as the Computer Hardware (or hardware). In other words, the physical equipments that are involved in the function of the computer are called its hardware. The computer hardware is typically divided into four main categories: Processing Devices, Memory Devices, Input/, Output Devices, and Storage Devices.

Processing Devices.

The Central Processing Unit (CPU)

The Central Processing Unit is an electronic device which runs computer programs: a set of sequential instructions. It is also called as the Computer Processor or the brain of thecomputer. Т here are two major componentsnamely the Control Unit (CU) and the Arithmetic and Logic Unit (ALU). The CU is the circuitry that controls the flow of data through the processor, and coordinates the activities of the other units within it. In a way, it is the "brain within the brain", as it controls what happens inside the processor, which in turn controls the rest of the PC. The ALU is a digital circuit that performs arithmetic and logical operations. The ALU is a fundamental building block of the central processing unit of a computer, and even the simplest microprocessors contain one, for purposes such as maintaining timers. The processors found inside modern CPUs have very powerful and very complex ALUs; a single component may contain a number of ALUs.

We consider the CPU as the processing device of the computer. You are aware that the CPU contains Control Unit (CU) and an Arithmetic and Logic Unit (ALU). These two components work together to perform the processing operations. On a PC, the CPU usually is contained on a single chip and sometimes is called Microprocessor. In addition to the CU and ALU, a microprocessor usually contains the registers and system clock.

The Control Unit (CU). As you know, a computer program or set of instructions must be stored in memory for a computer to process data. The CPU uses its CU to execute these instructions. Further, the CU directs and coordinates most of the operations of the computer. The speed at which the processorcarries out its operations is measured in megahertz (MHz). The higher the number of MHz the faster the computer can process information. The Intel i7, Athlon, Celron, and Duron, UltraSpark are some examples for the brands of processors available in the market.

The Arithmetic and Logic Unit (ALU). ALU performs the arithmetic, comparison, and logical operations. Arithmetic operations include addition (+), subtraction (-), multiplication (*) and division (/). Comparison operations include comparing one data item to another to determine if the first item is greater than (>), equal (=), or less than (<) to the second item. Logical operations work with conditions such as AND, OR, NOT.

Memory Devices

Computer Memory. A character is stored in the computer as a group of 0s and 1s, called a Byte. The size of the memory is measured by the number of bites available. The following equalities give the measuring units of the memory.

While performing a processing operation, a processor needs a place to temporarily store instructions to be executed and the data to be used with those instructions. The data and the instructions needed by the CPU are temporarily stored in the Memory. Therefore the memory acts as the internal storage of a computer. The programs that are stored in external storages are loaded into the memory before they start running.

Random Access Memory (RAM). The Random Access Memory (RAM) is a volatile form of a computer memory. This small memory is capable of memorizing temporarily. It can be read and written. That is, you can both write data into RAM and read data from RAM. Together with the CPU, RAM determines the computer's speed. A computer with a large RAM and a CPU can actually run faster than a computer with a powerful CPU but with a low RAM.