lesson2.1 computer components rev2

Lesson 2: COMPONENTS

OF A COMPUTER SYSTEM

Computer SystemComputer SystemA computer system consists of mainly four basic units: input unit, storage unit, central processing unit and output unit.

Central Processing unit further includes Arithmetic logic unit (ALU) and control unit (CU)

A computer performs five major operations or functions:

• it accepts data or instructions as input,• it stores data and instruction• it processes data as per the instructions,• it controls all operations inside a computer• it gives results in the form of output.

Computer System.. contComputer System.. cont

Basic Computer System Basic Computer System OrganizationOrganization

CPU

ALU

MEMORY UNIT

CU

INPUT OUTPUT

STORAGE

Functional Units:1.Input Unit. This unit is used for entering data and programs into the computer system by the user for processing.

2. Storage Unit. The storage unit is used for storing data and instructions before and after processing.

3.Output Unit. The output unit is used for storing the result as output produced by the computer after processing.

4. 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. CPU includes Arithmetic logic unit (ALU) and control unit (CU)

Functional Units… cont.

• Control Unit - controls all operations like input, processing and output. -It takes care of step by step processing of all operations in side the computer.

•Arithmetic Logic Unit- all calculations and comparisons, based on the instructions provided, are carried out. - it performs arithmetic functions like addition, subtraction, multiplication, division and also logical operations like greater than, less than equal to, and etc.

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. CPU includes Arithmetic logic unit (ALU) and control unit (CU)


5. Primary and Secondary Storagea. primary storage

a.1 RAM a.2 ROM

b. secondary storageb.1. magnetic disk

b.2. magnetic tape b.3. optical disk b.4. punched card.


a. Primary Storage

a.1. RAM or Random Access Memory

- It is the place in a computer where the operating system, application programs and the data in current use are kept temporarily so that they can be accessed by the computer’s processor.


a. Primary Storagea.1. RAM or Random Access Memory

- It is said to be ‘volatile’ since its contents are accessible only as long as the computer is on. The contents of RAM are no more available once the computer is turned off

•


a. Primary Storage

a.2. ROM or Read Only Memory -is a special type of memory which can only be read and contents of which are not lost even when the computer is switched off.


a. Primary Storage

a.2. ROM or Read Only Memory -It typically contains manufacturer’s instructions. Among other things, ROM also stores an initial program called the ‘bootstrap loader’ whose function is to start the operation of computer system once the power is turned on.


b. Secondary Storage- devices and peripherals that are

connected and controlled by the computer to enable permanent storage of programs and data. e.g. Magnetic disks and optical disks


b. Secondary Storageb.1. Magnetic disks

b.1.1. Hard Disk - made up of rigid material and are usually a stack of metal disks sealed in a box.

- the hard disk and the hard disk drive exist together as a unit and is a permanent part of the computer where data and programs are saved.



b.1.1. Hard Disk - these disks have storage capacities ranging from 1GB to 80 GB and more. - rewritable.



b.1.3. Floppy disk - a disk storage medium composed of a disk of thin and flexible magnetic storage medium, sealed in a rectangular plastic carrier lined with fabric that removes dust particles.



b.1.3. Floppy disk - floppy disks are read and written by a floppy disk drive (FDD).

- floppy disks, initially as 8-inch media (360 KB) and later in 5¼-inch (1.2 MB) and 3½-inch (1.44 MB) sizes, were a ubiquitous form of data storage.


b. Secondary Storageb.2. Optical disks

b.2.1. Compact Disk (CD) - a portable disk having data storage capacity between 650-700 MB.

- It can hold large amount of information such as music, full-motion videos, and text etc.

- CDs can be either read only or read write type.



b.2.2. Digital Video Disk (DVD) - is similar to a CD but has larger storage capacity and enormous clarity (high video and sound quality).

- can store several Gigabytes of data.

- DVDs are primarily used to store music or movies and can be played back on your television or the computer too.

- not rewritable.



b.2.3. Blu-ray Disc (BD) - designed to supersede the DVD format

- capable of storing high-definition video resolution (1080p)

- contain 25 GB per layer, with dual layer discs (50 GB) being the industry standard for feature-length video discs. Triple layer discs (100 GB) and quadruple layers (128 GB) are available for BD-XL re-writer drives



b.2.3. Blu-ray Disc (BD) - the name Blu-ray

Disc refers to the blue laser used to read the disc, which allows information to be stored at a greater density than is possible with the longer-wavelength red laser used for DVDs.



b.2.3. Blu-ray Disc (BD) - the major application of

Blu-ray Discs is as a medium for video material such as feature films and physical distribution of video games for the PlayStation 3 and 4, and Xbox One.



b.2.3. Blu-ray Disc (BD) - associated with a set of

multimedia formats. - these formats allow for

the option of video and audio to be stored with greater definition than on DVD.


b. Secondary Storageb.3. Magnetic tapes

b.3.1. Magnetic tape data storage

- is a system for storing digital

information on magnetic tape using digital recording. - modern magnetic tape is

most commonly packaged in cartridges and cassettes.


6. Other Storage Devices 6.1. Secondary Storage

b.3. Paper Medium

b.3.1. Punched Cards - punched card, punch

card, IBM card, or Hollerith card- a piece of stiff paper that

contained either commands for controlling automated machinery or data for data processing applications.



b.3. Paper Medium

b.3.1. Punched Cards - both commands and

data were represented by the presence or absence of holes in predefined positions.



6.1.1. Pen drive - flash memory with an integrated Universal Serial Bus (USB) interface. - flash drives are typically removable and rewritable, and physically much smaller than any secondary storage. - faster, have thousands of times more capacity, and are more durable and reliable because they have no moving parts. - immune to magnetic interference (unlike floppy disks), and unharmed by surface scratches (unlike CDs).

- faster, have thousands of times more capacity, and are more durable and reliable because they have no moving parts.

- immune to magnetic interference (unlike floppy disks), and unharmed by surface scratches (unlike CDs).



6.1.2. Pen drive - smaller, faster, have thousands of times more capacity, and are more durable and reliable because they have no moving parts.

- immune to magnetic interference (unlike floppy disks), and unharmed by surface scratches (unlike CDs).

lesson2.1 computer components rev2

Software