1. Basics of Computing
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2. -device that process data according to a set of stored instructions
- What is a Computer?
A computer is an electronic device used to accept input data, process input data, store and produce desired output results.
-device that process data according to a set of stored instructions
Computers process data under the control of sets of instructions called computer programs
A complete computer system includes four distinct parts:
Hardware
Software
Data
User
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4. The Parts of a Computer System - Hardware
A computer's hardware consists of electronic devices or parts that you can see and touch(Physical components)
The term "device" refers to any piece of hardware used by the computer, such as a keyboard, monitor, modem, mouse, drives etc etc.
While a peripheral is a piece of equipment that is/can be connected to a computer
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6. The Parts of a Computer System - Software
Software – also called programs – consists of organized sets of instructions for controlling the computer.
Some programs exist for the computer's use, to help it manage its own tasks and devices – Operating system Software. (provides link btn hardware, user and software )eg unix, linux,ubuntu, MS Windows family,Android,mm
Other programs enable the computer to perform tasks for you (user), such as creating documents
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7. The Parts of a Computer System - Data
Data consists of raw facts and figures, which the computer can manipulate and process into information that is useful to people.
Computerized data is digital, meaning that it has been reduced to digits, or numbers. The computer stores and reads all data as digits.
Although computers use data in digital form, they convert data into forms that people can understand, such as text, numerals, sounds, and images.
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8. The Parts of a Computer System – Users
People are the computer's operators, or users.
Some types of computers can operate without much intervention from people, but personal computers are designed specifically for use by people.(users)
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9. Looking Inside the Machine - The CPU
The procedure of transforming raw data into useful information is called processing. This function is divided between the computer's processor and memory.
The processor is also called the central processing unit (CPU). It manages all devices and performs the actual processing of data.
The CPU consists of one or more chips attached to the computer's main circuit board (the motherboard).
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10.
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11. Memory
The memory dictates the processing capacity of a PC. Capacity is calculated in KB, MB, GB.
There are two types of memory : ROM & RAM.
RAM(Random Access Memory)-- memory that holds data & program instructions as the CPU is in process . Or memory that is directly available to the processing unit.
The CPU can find any piece of data in RAM, when it needs it for processing.
RAM is volatile , meaning it holds data only when the power is on. When the power
is off, volatile RAM's contents are lost.
CACHE: a small but extremely fast memory chip, saves as a copy of pieces of data most recently read from or written to main memory. When Cache is full, old entries ‘re flushed out.
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12. How Computers Process Data - Types of RAM
There are two basic types of RAM: static and dynamic
Dynamic RAM (DRAM) chips must be recharged
with electricity very frequently, or they will lose their
contents.
Static RAM (SRAM) does not need to be recharged
as often as DRAM, and can hold its contents longer.
Another type of RAM, called flash memory, can store its contents after power is turned off. Flash memory is used in devices such as digital cameras to store pictures.
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13. Memory
ROM(Read Only Memory)-is the memory chip into which fixed data is written permanently at the time of its manufacture.
ROM is always non-volatile, meaning data is not lost even if when power is off.
ROM is used to store small but important programs that are run when the computer starts up via the BIOS
BIOS(Basic Input/ Output system)-part of memory chip with programs needed for controlling keyboard, disk drives, monitor, mouse
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14. How Computers Represent Data
Binary Numbers
The Binary Number System
Bits and Bytes
Text Codes
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15. How Computers Represent Data – Binary Numbers
All computer data is converted to a series of binary numbers– 1 and 0.
Computer processing is performed by transistors, which are switches with only two possible states: on and off. (1 and 0)
For example, you see a sentence as a collection of letters, but the computer sees each letter as a collection of 1s and 0s.
If a transistor is assigned a value of 1, it is on. If it has a value of 0, it is off. A computer's transistors can be switched on and off millions of times each second.
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16. The Binary Number System
Base 10
Base 2 1 2 10 3 11 4
100 5
101 6
110 7
111 8
1000 9
1001
1010
The binary number system works the same way as the decimal system, but has only two available symbols (0 and 1) rather than ten (0, 1, 2, 3, 4, 5, 6, 7, 8, and 9).
Humans use the decimal system (“deci” stands for “ten”).
To convert data into strings of numbers, computers use the binary number system.
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17. How Computers Represent Data - Bits and Bytes
A Bit is a single unit of data, having a value of either 1 or 0.
Computers work with collections of bits, grouping them to represent larger pieces of data, such as letters of the alphabet.
Eight bits make up one byte. .
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18. byte
A byte is the amount of memory needed to store one alphanumeric character.
The smallest usable unit of measure for memory is the byte – the amount of
memory required to hold one character, like the letter A or the numeral 2.
With one byte, the computer can represent one of 256 different symbols or characters.
Computers work with larger chunks of data, measured in multiple bytes, as shown below:
Unit Approx. Value (bytes) Actual Value (bytes)
KiloByte (KB) 1,000 =2^10 1,024
MegaByte (MB) ,000, =2^20 1,048,576
GigaByte (GB) 1,000,000, =2^30 1,073,741,824
TeraByte (TB) 1,000,000,000, =2^40 1,099,511,627,776
PentaByte =2^50
ExaByte =2^60
ZettaByte =2^70
YottaByte (IBM Dictionary for Computing)
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19. How Computers Represent Data - Text Codes
A text code is a system that uses binary numbers (1s and 0s) to represent characters understood by humans (letters and numerals).
The most common text-code set in use is the , ASCII, each character consists of eight bits (one byte) of data. ASCII is used in nearly all personal computers.
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20. INPUT AND OUTPUT DEVICES
ANY QUESTIONS
INPUT AND OUTPUT
DEVICES
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21. INPUT AND OUTPUT DEVICES
Input devices are hardware components that facilitate the capture of data into the computer systems through standard input ports. These ports can either be serial or USB. Keyboard, mouse –most common input devices.
Students give e.gs
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22. INPUT DEVICE(Keyboard)
Most keyboards use the QWERTY layout, named after?? It is used for the manual capture of data
into the computer system
The advantages of using a keyboard for the input of data.
The person keying in the data can be in a remote location, away from the computer itself.
Data can be transmitted via a communications link
The person keying in the data can check for keying errors on-screen.
Keyboard input is convenient for small volumes of data input.
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23. The disadvantages of a keyboard for data capture
INPUT DEVICE(Keyboard)
The disadvantages of a keyboard for data capture  
It is unsuitable for large volumes of transaction data.
Keying data manually takes time, so is not appropriate in some situations.
Keyboard input is likely to be error-prone
There might be security problems, there is the risk that unauthorised people could access a terminal or PC
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24. INPUT DEVICE(Mouse)
The mouse is a pointing device. You use it to move a graphical pointer on the screen.
The mouse can be used to issue commands, draw, and perform other types of input tasks. Types of mice: Trackballs, Trackpads, laser, infra etc
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25. The disadvantages of a keyboard for data capture
INPUT DEVICE(Keyboard)
The disadvantages of a keyboard for data capture  
It is unsuitable for large volumes of transaction data.
Keying data manually takes time, so is not appropriate in some situations.
Keyboard input is likely to be error-prone
There might be security problems, there is the risk that unauthorised people could access a terminal or PC
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26. Alternative(Automatic) Input Devices
MICR: involves the recognition by a machine of special formatted character printed in ink.
very speedy and accurate. Used mainly in banks on Cheques and Deposit slips
Bar code readers can read bar codes—patterns of printed bars.
The reader emits light, which reflects off the bar code and into a detector in the reader. The detector translates the code into numbers. Commonly found in supermarkets. Couriers  
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27. Alternative(Automatic) Input Devices
OMR
- involves the marking of pre printed form with a pen/typed.
-used in marking A,B,C,D answer sheets, National Lottery.
OCR
-can be classified as just special scanners.
 A scanner shines light onto the image and interprets the reflection.
Optical character recognition (OCR) software translates scanned text into editable electronic documents.
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28. Alternative(Automatic) Input Devices
Smart card Reader- Reads smart cards
A smart card-a plastic card in which is embedded a microprocessor chip.
Most common smart card applications-: credit/debit cards, computer security system, e-cash…etc
Voice Recognition devices
Visual/ Image Recognition devices
- mostly used in computer security systems(biometrics)
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29. Most common output devices include:
These hardware devices produce of display processed data or information to the outside world.
Most common output devices include:
Monitors(LCD/LED), printers – . Students give e.gs
TASK:
Research on printers: Types-impact and non impact
Dot Matrix Printers , Ink Jet Printers, Laser Printers , Snapshot Printers
Other High-Quality Printers
Criteria you should consider when evaluating printer
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