Data representation

what is data representation

method of encoding information in a format the computer can process

what are the basic building block in computers

binary number system with 1s and 0s

what is another name for binary number system

base 2

what is the representation of switches

on and off positions of 1s and 0s

what are logic gates in computers used for

to store and process data efficiently in computers

what is the other name for denary

base 10

what is the other name for hexadecimal

base 16

numbers in binary

0, 1

numbers in denary

0, 1, 2, 3, 4, 5, 6, 7, 8, 9,

what are the numbers in hexadecimal

0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F

convert 00110011 to denary

51

convert 01111111 to denary

127

convert 56 into binary

00111000

convert 10011001 into hexadecimal

99

convert 10110011 into hexadecimal

B3

convert F2 into denary

242

convert 6F into binary

01101111

why do computer scientists find hexadecimal ore convenient to use than binary

one hex digit represents four binary digits

what is 1101 0010 1010 1111

D2AF

what are four uses of hexadecimal

error codes, MAC address, IP address, HTML

what do error codes refer to

memory location of the error

who needs to know how to interpret error codes

the programmer

What is a MAC address

a number that uniquely identifies a device on a network

what is a MAC address made up of

48 bits shows as 6 groups of two hexadecimal digits

what do the two halves of a MAC address represent

first half is manufacturer’s identity number and second half is serial number of the device

difference between IPv4 and IPv6

IPv4 is 32-bit in denary or hexadecimal, IPv6 is 128-bit in hexadecimal

what is HTML used for

writing and developing web pages

how are colours represented in HTML

six hexadecimal digits preceded by # symbol

how many possible colours can be represented in HTML

over 16 million

write the format of MAC addresses

NN-NN-NN DD-DD-DD

which IP address uses colon

IPv6

benefits of HTML

takes less space, easier to read, 1 HTML digit is 4 binary digits

format of IPv6

broken down into 16-bit chunks with a colon separator

add 0101 and 1110

00010011

What is a logical binary shift?

It is moving a binary number to the left or right.

what does a shift left in binary mean

equivalent to multiplying the binary number by 2

what does a shift right in binary mean

equivalent to dividing the binary number by 2

What happens to empty positions in a binary number during a logical shift?

They are replaced with a zero.

shift 01110000 five places to the left

00000000

What is two’s complement used for in binary numbers?

It is used to represent negative integers.

How is the left-most bit interpreted in two’s complement

1 indicates negative, 0 indicates positive

range of numbers in two’s complement

−128 to +127

10000000 to 01111111

00110011 in two’s complement

51

11001111 in two’s complement

-49

what does ASCII stand for

American Standard Code for Information Interchange

when was ASCII set up

1963

How many bits are in the standard ASCII code character set?

7 bits

range of standard ASCII in denary and hexadecimal

0 to 127 in denary

00 to 7F in hexadecimal

how many control codes in ASCII

32

what is the range of the ASCII control codes in denary and hexadecimal

0 to 31 in denary

00 to 19 in hexadecimal

what are the limitations of logical binary shifts

limit to the number of shifts before all zeros in an 8-bit register

what is the main disadvantage of ASCII

does not represent non-western languages

what coding system developed ASCII limitations

unicode

how many characters can Unicode support compared to ASCII

several thousands over 128 characters

How many bytes per character does Unicode use compared to ASCII?

Unicode is four per character

ASCII is 1 per character

When was the Unicode consortium set up

1991

Unicode’s five goals

covering all languages, uniform encoding, more efficient, unambiguous encoding, reserve part of code

What are sound waves

Sound waves are vibrations in the air

how are sound waves interpreted by the human ear?

ear senses these vibrations in ear drum

Why do sound waves need to be sampled to be stored in a computer?

sound waves are analogue and computers cannot work with analogue data

What is sampling in the context of sound waves?

measuring the amplitude of the sound wave at regular time intervals

What tool is used to convert analogue sound waves to digital?

analogue to digital converter (ADC)

What is sampling resolution (bit depth)

number of bits used to represent each sampled amplitude value

How is sampling rate measured

measured in hertz (Hz)

what does the measurement of sampling rate signify

number of sound samples taken per second.

What happens when you use a higher sampling rate or larger resolution in sound sampling?

increases file size and produces more faithful representation

what are the benefits of large sample rate

better quality, less distortion, larger dynamic range

what does this represent

error codes

what does this represent

IPv6

what does this represent

HTML

what does this represent

HTML hex colour code

what does this represent

ACSII code

what is this

sound wave

what do these represent

different pixel shapes

what does this represent

different image resolution

which image has the highest resolution

image a

what do we call an image with a low resolution

pixilated

What is the sampling resolution of CD’s

16-bit

what is the sample rate of CD’s

44.1 kHz

How many samples per second does a CD take

44,100 every second

What is a bitmap image composed of?

pixels arranged in a two-dimensional matrix

How is each pixel in a bitmap image represented?

Pixels represented as a binary number.

How many bits per pixel are required for a black and white image?

1 bit per pixel.

How many colours can be represented with 2 bits per pixel?

Four colours

how are the four colours represented in 2 bits per pixel

00, 01, 10, 11

How many colours can be represented with 3 bits per pixel?

Eight colours

how are eight colours represented with 3 bit pixels

000, 001, 010, 011, 100, 101, 110, 111

What is colour depth

number of bits used to represent each colour in a pixel

How many colours can an 8-bit colour depth represent?

256 or 2^8

How many colours can a 24-bit colour depth represent

Over 16 million

What is image resolution?

number of pixels that make up an image.

How does increasing the colour depth affect file size?

increases colour depth, increases file size

What is the main drawback of using high-resolution images?

increase file size

How does the resolution of an image affect storage and transfer?

takes up more space on storage and longer to transmit

What happens to image quality when resolution is reduced?

loss of quality slowly becomes noticeable

What is the basic unit of all computing memory storage terms?

a bit

what does a bit consist of

either 1 or 0

What does the term "byte" refer to?

The smallest unit of memory in a computer

how much is a byte

8 bits

What is a 4-bit number called

a nibble