pComponents of the Computer
pDifferent usages of the computers
pVon Neumann Architecture
pData and information
pHow to store the data in a computer
pBasic Data Types
pNumber Representation
pFloating Point Representation
pData Representation in Computers
Binary Code TransmissionObjectives
pDifferentiate between data and Information
pIdentify the basic functions of the computer
pData representation inside computers
Components of the Computer
A Modern Computer System
Von Neumann Architecture
Von Neumann Architecture
pAll computers share the same basic architecture, whether it be a multi-million dollar mainframe or a Palm Pilot.
pAll have memory, an I/O system, and arithmetic/logic unit, and a control unit.
ain components of theVon
Neumann architecture
(1) CPU – Central Processing Unit
arithmetic-logic unit (ALU)
performs the computer's computational and logical functions
(2) control unit
directs other components of the computer to perform certain actions
(3) input and output devices
main-machine interfaces; i.e.,
(2) memory
the computer's main, or fast, memory, such as random access memory (RAM)
Data and Information
pWhat is Data ?
pData is a collection of facts
§Numbers
§Words
§Measurements
§Observations
§Description of things
pWhat is Information?
processed outcome of data. (it is derived from data)
How do we store data in a computer?
pComputer is a digital device which is capable to handle discrete data/information
pTherefore, we need to convert these analog signals to digital signals after capturing them by the input devices
pThis is done with the converter – Analogue to Digital Convertor (ADC)
pDigital signals are represented by numbers (Binary Digits) and need to be stored in the main memory
p8 Bits = 1 Byte
p1024 Bytes ＝ 1KB
p1024 KB = 1 MB
p1024 MB = 1 GB
p1024 GB = 1 TB
p The memory is made up of BYTES
p Each BYTE can be addressed uniquely
p When the address is expressed in Binary,
the number of maximum BITs used to write
the address specifies the total number of
locations available
p f n number of BITs are available then the total number of locations available is 2n
p If we have 32 BITs then we can have 4GB of Memory (232 ＝ 4 GB)
Programmers point of view
pProgrammers need to use data in their programs
pThe architecture says, it is required to store them in the main memory before use
pTherefore, it is required to find a way to put them in memory
pAs there may have differences in the data He sets his requirement through what we call a DATA TYPE
pThrough a data type, architecture tells the computer that data must be stored in a particulaway in the main memory
pFor that, the data must have a representation
Basic Data Types: Character Data
pNumeric
n0 1 2 … 9
pAlphabetic
na b c …… z
pSpecial
n# @ % ( $ &
Basic Data Types: Numeric data
pInteger
n+ & - whole numbers
n 4251 -582
pReal
nAll numbers including everything between integers
n 0.23, 0, 5½, -2.3,
pFixed Point Representation
n12.548
pFloating Point Representation
nScientific Notation
p12.054 à 1.2054 * 101
nComputer Notation
p12.65 à 0.1265*102
Parity: Odd & Even Parity
pComputers can sometimes make errors when they
transmit data.
pEven/odd parity:
nis basic method for detecting if an odd number of bits has been switched by accident.
pOdd parity:
nThe number of 1-bit must add up to an odd number
pEven parity:
The number of 1-bit must add up to an even number
Parity: Odd & Even Parity(Contd.)
pIt is useful when an odd number of 1-bits is flipped.
pSuppose we have an 7-bit binary word (7-digits).
nIf you need to change the parity you need to add 1 (parity bit) to the binary word
nYou now have 8 digit word.
nHowever, the computer knows that the added bit is a parity bit and therefore ignore it.
Parity Checking
pAssume we are using even parity with 7-bit ASCII.
pThe letter V in 7-bit ASCII is encoded as 0110101.
pHow will the letter V be transmitted?
nBecause there are four 1s (an even number), parity is set to zero.
nThis would be transmitted as: 01101010.
pIf we are using an odd parity:
The letter V will be transmitted as 01101011
n12.548
pFloating Point Representation
nScientific Notation
p12.054 à 1.2054 * 101
nComputer Notation
p12.65 à 0.1265*102
Parity: Odd & Even Parity
pComputers can sometimes make errors when they
transmit data.
pEven/odd parity:
nis basic method for detecting if an odd number of bits has been switched by accident.
pOdd parity:
nThe number of 1-bit must add up to an odd number
pEven parity:
The number of 1-bit must add up to an even number
Parity: Odd & Even Parity(Contd.)
pIt is useful when an odd number of 1-bits is flipped.
pSuppose we have an 7-bit binary word (7-digits).
nIf you need to change the parity you need to add 1 (parity bit) to the binary word
nYou now have 8 digit word.
nHowever, the computer knows that the added bit is a parity bit and therefore ignore it.
Parity Checking
pAssume we are using even parity with 7-bit ASCII.
pThe letter V in 7-bit ASCII is encoded as 0110101.
pHow will the letter V be transmitted?
nBecause there are four 1s (an even number), parity is set to zero.
nThis would be transmitted as: 01101010.
pIf we are using an odd parity:
The letter V will be transmitted as 01101011
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