What are the main functional units of a digital computer

Functional Components of a Computer

Computer: A computer is a combination of hardware and software resources which integrate together and provides various functionalities to the user. Hardware are the physical components of a computer like the processor, memory devices, monitor, keyboard etc. while software is the set of programs or instructions that are required by the hardware resources to function properly.
There are a few basic components that aids the working-cycle of a computer i.e. the Input- Process- Output Cycle and these are called as the functional components of a computer. It needs certain input, processes that input and produces the desired output. The input unit takes the input, the central processing unit does the processing of data and the output unit produces the output. The memory unit holds the data and instructions during the processing.

Digital Computer: A digital computer can be defined as a programmable machine which reads the binary data passed as instructions, processes this binary data, and displays a calculated digital output. Therefore, Digital computers are those that work on the digital data.

Details of Functional Components of a Digital Computer

Interconnection between Functional Components

A computer consists of input unit that takes input, a CPU that processes the input and an output unit that produces output. All these devices communicate with each other through a common bus. A bus is a transmission path, made of a set of conducting wires over which data or information in the form of electric signals, is passed from one component to another in a computer. The bus can be of three types – Address bus, Data bus and Control Bus.

Following figure shows the connection of various functional components:

The address bus carries the address location of the data or instruction. The data bus carries data from one component to another and the control bus carries the control signals. The system bus is the common communication path that carries signals to/from CPU, main memory and input/output devices. The input/output devices communicate with the system bus through the controller circuit which helps in managing various input/output devices attached to the computer.

Functional Components and their Interconnections

Functional Components of a Computer

The basic functional components or elements of a digital computer system basically has the hardware and software. The hardware is the physical component/part such as a keyboard, mouse, monitor, etc. The software is the set of programs and instructions which perform several specific operations.

Both hardware and software together act as functional components. They help to complete the functional cycle which consists of input, processing, and output. Let us learn about the different functional components of a digital computer and their working and interconnections. Let us study the basic components of a computer.

1. Input Unit

The input unit basically includes the input devices and its operation is to take the input from the user. It converts the input data into binary code. As the computer understands only machine language (binary code).

Some important input devices are:

2. Central Processing Unit (CPU)

1. Arithmetic and Logical Unit

As the name suggests, this unit is responsible for performing arithmetic tasks like addition, subtraction, multiplication, division moreover, it also makes logical decisions like greater than less than, etc. And hence the name, the ‘brain’ of the computer.

This unit is responsible for looking after all the processing. It organizes and manages the execution of tasks of the CPU.

These are memory areas which the CPU directly uses for processing. So, it’s function is to store data from input or store data between calculations. In addition, it also stores the output results.

3. Memory

The parts of memory are:

Primary Memory

This is the internal memory that stores the data and instructions of the CPU. It is volatile in nature (data is lost when the power is disconnected).

The primary memory has two types:

RAM (Random Access Memory)

As per the name, data can be accessed randomly and quickly.

As per the name, data can be accessed randomly and quickly.

Secondary Memory

As we know that the primary memory is volatile therefore, we need some devices to store the data permanently so we use some external storage devices for this purpose which we name as the secondary memory. Some examples: CD, DVD, etc.

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4. Output Unit

The output unit basically involves the output devices and it gives the processed information as the output on the computer. The data which is processed is in binary form, so the output unit converts it to a form that the humans can understand.

Some important output devices are:

Digital Computer

As per the name, a digital computer works on digital data. It reads input and converts it into binary data. Further, it processes the data and produces binary results. And finally, it converts the binary data into digital output.

A digital computer

Interconnection Between Functional Components

After learning about the functional components we will learn about their interconnections. The functional components usually use a bus architecture for communication. A bus is a collection of wires used for the communication of different parts of a computer. Further, it uses electric signals to pass the data and information.

Different Types of Buses used are:

1. Address Bus

The address bus is used to communicate the address of the given data and instructions.

2.Data Bus

The data bus is used to communicate the data from one part to another.

The control bus is used to control the signals between different devices. Therefore, in conclusion, we can say that these functional components communicate through this bus architecture. The input device takes the input, then the data is processed and the output devices display the results. Besides, the system bus performs all the communication that the cycle involves.

Frequently Asked Questions (FAQs)

Q1. What are the types of memory?

A1. There are two types of memories:

Q2. What is the other name of the CPU?

A2. The CPU is also called the main processor or microprocessor.

Q3.What are the types of primary memory?

A3. There are two types of primary memory:

Q4. What is a digital computer?

A4. A digital computer is a machine that works on digital data. It takes binary input, processes it, and produces digital results.

Q5. What is the bus?

A5. A bus is a collection of wires which uses electric signals to communicate between functional components.

Q6. What are the parts of the CPU?

A6. The CPU consists of:

digital computer

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Read a brief summary of this topic

digital computer, any of a class of devices capable of solving problems by processing information in discrete form. It operates on data, including magnitudes, letters, and symbols, that are expressed in binary code—i.e., using only the two digits 0 and 1. By counting, comparing, and manipulating these digits or their combinations according to a set of instructions held in its memory, a digital computer can perform such tasks as to control industrial processes and regulate the operations of machines; analyze and organize vast amounts of business data; and simulate the behaviour of dynamic systems (e.g., global weather patterns and chemical reactions) in scientific research.

A brief treatment of digital computers follows. For full treatment, see computer science: Basic computer components.

Functional elements

A typical digital computer system has four basic functional elements: (1) input-output equipment, (2) main memory, (3) control unit, and (4) arithmetic-logic unit. Any of a number of devices is used to enter data and program instructions into a computer and to gain access to the results of the processing operation. Common input devices include keyboards and optical scanners; output devices include printers and monitors. The information received by a computer from its input unit is stored in the main memory or, if not for immediate use, in an auxiliary storage device. The control unit selects and calls up instructions from the memory in appropriate sequence and relays the proper commands to the appropriate unit. It also synchronizes the varied operating speeds of the input and output devices to that of the arithmetic-logic unit (ALU) so as to ensure the proper movement of data through the entire computer system. The ALU performs the arithmetic and logic algorithms selected to process the incoming data at extremely high speeds—in many cases in nanoseconds (billionths of a second). The main memory, control unit, and ALU together make up the central processing unit (CPU) of most digital computer systems, while the input-output devices and auxiliary storage units constitute peripheral equipment.

Development of the digital computer

Blaise Pascal of France and Gottfried Wilhelm Leibniz of Germany invented mechanical digital calculating machines during the 17th century. The English inventor Charles Babbage, however, is generally credited with having conceived the first automatic digital computer. During the 1830s Babbage devised his so-called Analytical Engine, a mechanical device designed to combine basic arithmetic operations with decisions based on its own computations. Babbage’s plans embodied most of the fundamental elements of the modern digital computer. For example, they called for sequential control—i.e., program control that included branching, looping, and both arithmetic and storage units with automatic printout. Babbage’s device, however, was never completed and was forgotten until his writings were rediscovered over a century later.

Of great importance in the evolution of the digital computer was the work of the English mathematician and logician George Boole. In various essays written during the mid-1800s, Boole discussed the analogy between the symbols of algebra and those of logic as used to represent logical forms and syllogisms. His formalism, operating on only 0 and 1, became the basis of what is now called Boolean algebra, on which computer switching theory and procedures are grounded.

John V. Atanasoff, an American mathematician and physicist, is credited with building the first electronic digital computer, which he constructed from 1939 to 1942 with the assistance of his graduate student Clifford E. Berry. Konrad Zuse, a German engineer acting in virtual isolation from developments elsewhere, completed construction in 1941 of the first operational program-controlled calculating machine (Z3). In 1944 Howard Aiken and a group of engineers at International Business Machines (IBM) Corporation completed work on the Harvard Mark I, a machine whose data-processing operations were controlled primarily by electric relays (switching devices).

Since the development of the Harvard Mark I, the digital computer has evolved at a rapid pace. The succession of advances in computer equipment, principally in logic circuitry, is often divided into generations, with each generation comprising a group of machines that share a common technology.

In 1946 J. Presper Eckert and John W. Mauchly, both of the University of Pennsylvania, constructed ENIAC (an acronym for electronic numerical integrator and computer), a digital machine and the first general-purpose, electronic computer. Its computing features were derived from Atanasoff’s machine; both computers included vacuum tubes instead of relays as their active logic elements, a feature that resulted in a significant increase in operating speed. The concept of a stored-program computer was introduced in the mid-1940s, and the idea of storing instruction codes as well as data in an electrically alterable memory was implemented in EDVAC (electronic discrete variable automatic computer).

The second computer generation began in the late 1950s, when digital machines using transistors became commercially available. Although this type of semiconductor device had been invented in 1948, more than 10 years of developmental work was needed to render it a viable alternative to the vacuum tube. The small size of the transistor, its greater reliability, and its relatively low power consumption made it vastly superior to the tube. Its use in computer circuitry permitted the manufacture of digital systems that were considerably more efficient, smaller, and faster than their first-generation ancestors.

The late 1960s and ’70s witnessed further dramatic advances in computer hardware. The first was the fabrication of the integrated circuit, a solid-state device containing hundreds of transistors, diodes, and resistors on a tiny silicon chip. This microcircuit made possible the production of mainframe (large-scale) computers of higher operating speeds, capacity, and reliability at significantly lower cost. Another type of third-generation computer that developed as a result of microelectronics was the minicomputer, a machine appreciably smaller than the standard mainframe but powerful enough to control the instruments of an entire scientific laboratory.

The development of large-scale integration (LSI) enabled hardware manufacturers to pack thousands of transistors and other related components on a single silicon chip about the size of a baby’s fingernail. Such microcircuitry yielded two devices that revolutionized computer technology. The first of these was the microprocessor, which is an integrated circuit that contains all the arithmetic, logic, and control circuitry of a central processing unit. Its production resulted in the development of microcomputers, systems no larger than portable television sets yet with substantial computing power. The other important device to emerge from LSI circuitry was the semiconductor memory. Consisting of only a few chips, this compact storage device is well suited for use in minicomputers and microcomputers. Moreover, it has found use in an increasing number of mainframes, particularly those designed for high-speed applications, because of its fast-access speed and large storage capacity. Such compact electronics led in the late 1970s to the development of the personal computer, a digital computer small and inexpensive enough to be used by ordinary consumers.

By the beginning of the 1980s integrated circuitry had advanced to very large-scale integration (VLSI). This design and manufacturing technology greatly increased the circuit density of microprocessor, memory, and support chips—i.e., those that serve to interface microprocessors with input-output devices. By the 1990s some VLSI circuits contained more than 3 million transistors on a silicon chip less than 0.3 square inch (2 square cm) in area.

The digital computers of the 1980s and ’90s employing LSI and VLSI technologies are frequently referred to as fourth-generation systems. Many of the microcomputers produced during the 1980s were equipped with a single chip on which circuits for processor, memory, and interface functions were integrated. (See also supercomputer.)

What are the basic functional units of a computer system? Explain it with the help of a diagram

A computer can process data, pictures, sound and graphics. They can solve highly complicated problems quickly and accurately. A computer as shown in Fig. performs basically five major computer operations or functions irrespective of their size and make. These are

1) it accepts data or instructions by way of input,

2) it stores data,

3) it can process data as required by the user,

4) it gives results in the form of output, and

5) it controls all operations inside a computer.

1. Input: This is the process of entering data and programs in to the computer system. You should know that computer is an electronic machine like any other machine which takes as inputs raw data and performs some processing giving out processed data. Therefore, the input unit takes data from us to the computer in an organized manner for processing.

2. Storage: The process of saving data and instructions permanently is known as storage. Data has to be fed into the system before the actual processing starts. It is because the processing speed of Central Processing Unit (CPU) is so fast that the data has to be provided to CPU with the same speed. Therefore the data is first stored in the storage unit for faster access and processing. This storage unit or the primary storage of the computer system is designed to do the above functionality. It provides space for storing data and instructions.

The storage unit performs the following major functions:

3. Processing: The task of performing operations like arithmetic and logical operations is called processing. The Central Processing Unit (CPU) takes data and instructions from the storage unit and makes all sorts of calculations based on the instructions given and the type of data provided. It is then sent back to the storage unit.

4. Output: This is the process of producing results from the data for getting useful information. Similarly the output produced by the computer after processing must also be kept somewhere inside the computer before being given to you in human readable form. Again the output is also stored inside the computer for further processing.

5. Control: The manner how instructions are executed and the above operations are performed. Controlling of all operations like input, processing and output are performed by control unit. It takes care of step by step processing of all operations inside the computer.

FUNCTIONAL UNITS

In order to carry out the operations mentioned in the previous section the computer allocates the task between its various functional units. The computer system is divided into three separate units for its operation. They are

1) arithmetic logical unit

3) central processing unit.

Arithmetic Logical Unit

Logical Unit :After you enter data through the input device it is stored in the primary storage unit. The actual processing of the data and instruction are performed by Arithmetic Logical Unit. The major operations performed by the ALU are addition, subtraction, multiplication, division, logic and comparison. Data is transferred to ALU from storage unit when required. After processing the output is returned back to storage unit for further processing or getting stored.

Control Unit (CU)

The next component of computer is the Control Unit, which acts like the supervisor seeing that things are done in proper fashion. Control Unit is responsible for co ordinating various operations using time signal. The control unit determines the sequence in which computer programs and instructions are executed. Things like processing of programs stored in the main memory, interpretation of the instructions and issuing of signals for other units of the computer to execute them. It also acts as a switch board operator when several users access the computer simultaneously. Thereby it coordinates the activities of computer’s peripheral equipment as they perform the input and output.

Central processing unit

The ALU and the CU of a computer system are jointly known as the central processing unit. You may call CPU as the brain of any computer system. It is just like brain that takes all major decisions, makes all sorts of calculations and directs different parts of the computer functions by activating and controlling the operations.

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FUNCTIONAL UNITS OF DIGITAL COMPUTERS

As we know, all computer operations can be grouped into five functional categories. The method in which these five functional categories are related to one another represents the functional organization of a digital computer. By studying the functional organization, a broad view of the computer is received.

The five major functional units of a digital computer are:

1) Input— to insert outside information into the machine;

2) Storage or memory — to store information and make it avail­
able at the appropriate time;

3)Arithmetic-logical unit — to perform the calculations;

4) Output — to remove data from the machine to the outside world and

5) Control unit — to cause all parts of a computer to act as a team.

Figure 5 shows how the five functional units of the comput­er act together. A complete set of instructions and data are usu­ally fed through the input equipment to the memory where they are stored. Each instruction is then fed to the control unit. The control unit interprets the instructions and issues commands to the other functional units to cause operations to be performed on the data. Arithmetic operations are performed in the arith­metic-logical unit, and the results are then fed back to the memory. Information may be fed from either the arithmetic unit or the memory through the output equipment to the outside world. The five units of the computer must communicate with each other. They can do this by means of a machine language which uses a code composed of combinations of electric pulses. These pulse combinations are usually represented by zeros and ones, where the one may be a pulse and the zero — a no-pulse. Num­bers are communicated between one unit and another by means of these one-zero or pulse — no-pulse combinations. The in­put has the additional job of converting the information fed in by the operator into machine language. In other words, it translates from our language into the pulse — no-pulse combinations understandable to the computer. The output’s additional job is converting the pulse — no-pulse combinations into a form un­derstandable to us, such as a printed report.

Просмотрите текст еще раз. Дайте ответы на вопросы, используя информацию текста.

1. What represents the functional organization of a comput­er? 2. What can we get by studying the functional organization? 3. What is the function of the input device? 4. What does mem­ory serve for? 5. What is the task of the arithmetic-logical unit? 6. What is the function of the output? 7. What is the main pur­
pose of the control unit? 8. How do all units of the computer
communicate with each other? 9. What is the additional job of
the input? 10. What is the additional function of the output?

4. Найдите втексте английскиеэквиваленты следующих
словосочетаний:

Функциональная организация; действия компьютера; связывать друг с другом; вводить информацию извне; де­лать информацию доступной; выполнять вычисления; выводить информацию; блок управления; выдавать коман­ды; заставлять выполнять команды; выходное устройство; внешний мир; связываться друг с другом; комбинация электрических импульсов; холостой импульс; импульсы, распознаваемые компьютером.

5.Разделите приведенные ниже слова на три группы, определяя по суффиксу часть речи — существительное, прилагательное или наречие. Переведите слова.

Organization, functional, available, equipment, processor, completely, architectural, converter, convertible, controller, re­movable, logical, addition, additional, usually, accomplishment, operator, operation, mainly, communication, insertion, elec­tronic, digital, instruction, generally, arithmetic, daily», develop­ment, central, lately, visible, substitution, understandable.

6. Вспомните значение новых слов и попытайтесь переве­сти словосочетания, употребляемые с этими словами.

Computer, analog computer; digital computer; hybrid com­puter; all-purpose computer; general-purpose computer; fifth-generation computer; game computer; handheld computer; mobile computer; multimedia computer; notebook computer; pocket computer; portable computer.

Unit: unit of memory; unit of data; unit of measurement; arithmetic unit; arithmetic-logical unit; central processing unit; computing unit; control unit; functional unit; input unit; out­put unit; network unit; system unit.

Function: arithmetic function; checking function; complex function; computer function; continuous function; conversion function; distribution function; encoding function; logical func­tion; numeric function; output function; program function; search function; software function; support function; utility function; variable function.

Control: access control; batch control; coding control; dis­tance / remote control; error control; execution control; hard­ware control; input/output control; memory control; power control; production control; program control; rate control; self-acting control; software control; system control.

7. Вспомните значение следующих прилагательных и пре­образуйте их в сравнительную и превосходную степени.

A. Small; fast; new; long; late; wide; young; easy; great; dull;
rich; bulky; large; vast; early; old; broad.

B. Frequent; reliable; approximate; significant; intricate;
possible; basic; remarkable; common; modern; dependent; general; necessary; successful; scientific; universal.