Identify the peripherals of a computer, components in a CPU and its functions. Draw the block diagram of the CPU along with the configuration of each peripheral.

AIM: To identify the peripherals of a computer.

Block Diagram Of Computer:

 

A computer can process data, pictures, sound and graphics. They can solve highly complicated problems quickly and accurately.

Input Unit:
Computers need to receive data and instruction in order to solve any problem. Therefore we need to input the data and instructions into the computers. The input unit consists of one or more input devices. Keyboard is the one of the most commonly used input device. Other commonly used input devices are the mouse, floppy disk drive, magnetic tape, etc. All the input devices perform the following functions.

1. Accept the data and instructions from the outside world.
2. Convert it to a form that the computer can understand.
3. Supply the converted data to the computer system for further processing.

Storage Unit:
The storage unit of the computer holds data and instructions that are entered through the input unit, before they are processed. It preserves the intermediate and final results before these are sent to the output devices. It also saves the data for the later use.

The various storage devices of a computer system are divided into two categories.
1. Primary Storage: Stores and provides very fast. This memory is generally used to hold the program being currently executed in the computer, the data being received from the input unit, the intermediate and final results of the program. The primary memory is temporary in nature. The data is lost, when the computer is switched off. In order to store the data permanently, the data has to be transferred to the secondary memory.The cost of the primary storage is more compared to the secondary storage. Therefore most computers have limited primary storage capacity.
2. Secondary Storage: Secondary storage is used like an archive. It stores several programs, documents, data bases etc. The programs that you run on the computer are first transferred to the primary memory before it is actually run. Whenever the results are saved, again they get stored in the secondary memory. The secondary memory is slower and cheaper than the primary memory. Some of the commonly used secondary memory devices are Hard disk, CD, etc.,

Memory Size:
All digital computers use the binary system, i.e. 0’s and 1’s. Each character or a number is represented by an 8 bit code.
The set of 8 bits is called a byte. A character occupies 1 byte space.
A numeric occupies 2 byte space.

Byte is the space occupied in the memory.

The size of the primary storage is specified in KB (Kilobytes) or MB (Megabyte). One KB is equal to 1024 bytes and one MB is equal to 1000 KB. The size of the primary storage in a typical PC usually starts at 16 MB. PCs having 32 MB, 48 MB, 128 MB, 256 MB memory are quite common.

Output Unit:
The output unit of a computer provides the information and results of a computation to outside world. Printers, Visual Display Unit (VDU) are the commonly used output devices. Other commonly used output devices are floppy disk drive, hard disk drive, and magnetic tape drive.

Arithmetic Logical Unit:

All calculations are performed in the Arithmetic Logic Unit (ALU) of the computer. It also does comparison and takes decision. The ALU can perform basic operations such as addition, subtraction, multiplication, division, etc and does logic operations viz, >, <, =, ‘etc. Whenever calculations are required, the control unit transfers the data from storage unit to ALU once the computations are done, the results are transferred to the storage unit by the control unit and then it is send to the output unit for displaying results.

Control Unit:

It controls all other units in the computer. The control unit instructs the input unit, where to store the data after receiving it from the user. It controls the flow of data and instructions from the storage unit to ALU. It also controls the flow of results from the ALU to the storage unit. The control unit is generally referred as the central nervous system of the computer that control and synchronizes its working.

Central Processing Unit:
The control unit and ALU of the computer are together known as the Central Processing Unit (CPU). The CPU is like brain performs the following functions:
• It performs all calculations.
• It takes all decisions.
• It controls all units of the computer.
A PC may have CPU-IC such as Intel 8088, 80286, 80386, 80486, Celeron, Pentium, Pentium Pro, Pentium II, Pentium III, Pentium IV, Dual Core, and AMD etc.

Introduction to Computer Hardware:

Hardware is the physical appearance of the devices or tools. It is what which we can touch and feel.

Computer Hardware consists of the Monitor, CPU, Keyboard, Mouse and all other devices connected to the computer either externally or internally.

A typical computer (personal computer, PC) consists of a desktop or tower case (chassis) and the following parts:

1. CPU The central processing unit contains the heart of any computer, the processor. The processor is fitted on to a Mother Board. The Mother Board contains various components, which support the functioning of a PC.

2.       System board/Motherboard which holds the Processor, Random Access Memory and other parts, and has slots for expansion cards

3. RAM (Random Access Memory)- For program execution and short term data-storage, so the computer doesn't have to take the time to access the hard drive to find something. More RAM can contribute to a faster PC.

The main memory of the computer is called as Random Access Memory (RAM). The name derives from the fact that data can be stored in and retrieved at random, from anywhere in the electronic main memory chips in approximately the same amount of time, no matter where the data is. Main memory is in an electronic or volatile state. When the computer is off, main memory is empty, when it is on it is capable of receiving and holding a copy of the software instructions, and data necessary for processing .Because the main memory is a volatile form of storage that depends on electric power can go off during processing, users save their work frequently on to non volatile secondary storage devices such as diskettes or hard disk.

 

The main memory is used for the following purposes:

1. Storage of the copy of the main software program that controls the general operation of the computer. This copy is loaded on to the main memory when the computer is turned on, and it stays there as long as the computer is on.
2. Temporary storage of a copy of application program instruction, to be received by CPU for interpretation and processing or execution.
3. Temporary storage of data that has been input from the key board, until instructions call for the data to be transferred in to CPU for processing.

Temporary storage of data, which is required for further processing or transferred as output to output devices such as screen, a printer, a disk storage device.

ROM (Read Only Memory)

Instructions which are critical to the operation of a computer are stored permanently on Read only Memory. (ROM) chip installed by the manufacturer inside the computer. This ROM chip is also called firm ware, retains instructions in a permanently accessible nonvolatile form. When the power in the computer is turned off, the instructions stored in ROM are not lost.
It is necessary and also convenient to have instructions stored in ROM. The more instructions in ROM, the fewer diskettes you may have to handle. Until recently the process of manufacturing ROM chips and recording data on them was more expensive than the process of producing RAM chips. As a result the manufacturers tended to record in ROM only those instructions that were crucial to the operation of the computer. Today, due to improvements in the manufacturing process of ROM chips have lowered the cost to the point where manufacturers are beginning to include additional software instructions.

In addition to ROM, three additional categories of non volatile memory are used in some computer systems. They are PROMs, EPROMs, and EPROMs. PROM stands for programmable read only memory. It works similar to that of ROM. PROM chips are custom made for the user by the manufacturer. The user determines what data and instructions are to be recorded on them. The data on PROM is permanent and cannot be erased. Erasable programmable read only memory (EPROM), developed as an improvement over PROM. The data on the EPROM can be read with the help of a special device that uses ultra violet light. The data or instructions on the EPROM are erasable and new data can be entered in its place. EPROM functions exactly same as PROM.Electronically erasable programmable read only memory (EEPROM) avoids the inconvenience of having to take chips out of the computer to change data and instructions. Changes can be made electrically under software control. These are used in point of sale terminals to records price related data for products. The prices recorded on them can be easily updated as needed. The only disadvantage of EEPROM is, the regular ROM chips.

Differences between   ROM &RAM

ROM (Read only memory)

1. You can only read the data.
2. Data can’t be written every time, to write the data we need PROM, EPROM, OR EEPROM.
3. ROM is non volatile in nature. The data stored in ROM is permanent in nature.
4. Size of the ROM has nothing to do with processing.

RAM (Random access memory):

1. You can read and write data on the chip.
2. RAM has volatile memory. It looses its contents when the power is switched off.
3. Size of the RAM makes difference in the processing i.e., bigger the size of the RAM more is the speed of processing.
4. The data can be read and written at anytime.

Dynamic RAM (DRAM)

                         

o   Synchronous DRAM (SDRAM)

                                 
           

                 

o   Static RAM (SRAM)

                                           

4.Buses : PCI bus, PCI-E bus, ISA bus (outdated), USB, AGP

            

                                     

5.       Power Supply - a case that holds a transformer, voltage control and fan

 

6.      Storage controllers, of IDE, SCSI or other type, that control hard disk, floppy disk, CD-ROM and other drives; the controllers sit directly on the motherboard (on-board) or on expansion cards

7.        Video display controller that produces the output for the computer display

8.       computer bus controllers (parallel, serial, USB, Fire wire) to connect the computer to external peripheral devices such as printers or scanners

9.       Some type of a removable media writer:      CD-ROM, , CD-RW,  CD-R,  DVD,  DVD-ROM

10.     CD - the most common type of removable media, cheap but fragile.

      CD-ROM, , CD-RW,  CD-R,  DVD,  DVD-ROM.,  DVD-RW,  DVD-R,

       

                                      

11. Floppy disk

Floppy Disk Drive

                                    

12. Tape Drive - mainly for backup and long-term storage

13. Internal storage - keeps data inside the computer for later use.

14. Hard disk - for medium-term storage of data.

                 

15. Disk array controller

                                         

16. Sound card - translates signals from the system board into analog voltage levels, and has terminals to plug in speakers.

 

17. Networking - to connect the computer to the Internet and/or other computers.

18. Modem - for dial-up connections

                                     

                         

                   

19. Network card - for DSL(Digital Subscriber Line)/Cable internet, and/or connecting to other computers.

                                

20.Other peripherals: In addition, hardware can include external components of a computer system. The following are either standard or very common.

Mouse

                               

                      

Alternate input devices:

 Pens,Touch screens,Game controllers(joy stick),Touch pad,Trackball.

Optical  input devices:  Barcode reader, Image scanners.

Audio visual input devices: Microphones, Video input ,Digital cameras

         

21. Output : The output devices are:

Standard output devices: Monitor

Types of monitors

CRT(cathode ray tube) monitors

 

LCD(liquid crystal display) monitors

Printer

Types of printers

Impact printers: An impact printer create an image by using pins or hammers to press an inked ribbon against the paper.ex. Dot matrix printer.

Non impact printers: This type uses other means to create an image for example in ink jet printers tiny nozzles are used to spray droplets of ink on the page.ex: Ink jet printer

LASER PRINTER

                                     

DOT MATRIX PRINTER

 Ink jet printer

Other output devices:

Speakers, LCD projectors, Networking, Network card

Speakers

  

LCD Projectors: