Intro and Chapter 1 Data representation

Question 1

What are the major components of a personal computer (PC)?

Answer 1

Computer case, computer case fan, motherboard, central processing unit (CPU), CPU cooling fan, power supply unit (PSU), random access memory (RAM), graphics card, hard drive (or SSD), optical drive (often without)

Question 2

What is the purpose of a computer case?

Answer 2

Stores all other components, prevents too much dust getting into them

Question 3

What is the purpose of a computer case fan?

Answer 3

Spins to keep components within case cool

Question 4

What is the purpose of a motherboard?

Answer 4

Allows components to be connected and communicate, allows them to receive power from PSU

Question 5

What is the purpose of a central processing unit (CPU)?

Answer 5

Responsible for operation of each fetch-decode-execute cycle carried out

Question 6

What is the purpose of a CPU cooling fan?

Answer 6

Cools CPU and prevents it from getting too hot, keeping it at best temperature to operate

Question 7

What is the purpose of a power supply unit (PSU)?

Answer 7

Powers motherboard to allow it to pass power to other components

Question 8

What is the purpose of random access memory (RAM)?

Answer 8

Temporarily stores data waiting to be processed

Question 9

What is the purpose of a graphics card?

Answer 9

Responsible for producing images seen on computer screen

Question 10

What is the purpose of a hard drive?

Answer 10

Permanently stores all files and software used

Question 11

What do most computers have to store files and software permanently? (choice)

Answer 11

A hard disk drive (HDD) or a solid state drive (SSD)

Question 12

What is the purpose of an optical drive?

Answer 12

Device in which optical media, like CDs, is inserted into, to be read by the computer

Question 13

What is hexadecimal, what does it use and why is it used?

Answer 13

A base-16 number system using values 0-9 and characters A-F, used to represent values for programmers, takes up less space on screen or paper, easier for programmers to read, write, understand, easier to debug and locate errors in data

Question 14

What is binary and what does it use?

Answer 14

A base-2 number system using the values 0 and 1, where the units increase by the power of 2

Question 15

What is analogue data?

Answer 15

A continuous stream of data processed by humans

Question 16

What is a logic gate and what data can they process?

Answer 16

A very small component in a computer system controlling electricity flow that can only process digital data

Question 17

What is digital data and what does it use?

Answer 17

Discrete data that only has values 1 and 0

Question 18

What is a register?

Answer 18

A small component in a computer system used to temporarily store data

Question 19

What is denary and what does it use?

Answer 19

A base-10 number system using values 0 - 9

Question 20

What values does a computer system use?

Answer 20

Binary number system

Question 21

How is a binary number referred to in relation to the number of bits it has, and what are these?

Answer 21

4-bit binary number has 4 values either 1 or 0, 8-bit binary number has 8 values either 1 or 0

Question 22

How do you convert a denary number to binary?

Answer 22

Compare the denary number to the first (leftmost) binary unit, if the denary is greater subtract the binary unit from it, write a 1 in that position, and move to the next binary unit. If the denary is smaller, write a 0 and move on with no subtraction. Repeat until the end of the binary units is reached

Question 23

How do you convert a binary number to denary?

Answer 23

Add together all units in the binary number represented by the value 1

Question 24

How are denary numbers converted to hexadecimal generally?

Answer 24

Denary numbers less than 16 can be directly converted to hexadecimal, greater than 16 numbers generally converted to binary first, then to hexadecimal, using 4-bit binary numbers

Question 25

How is hexadecimal converted to denary?

Answer 25

Hexadecimal numbers less than 16 can be converted to denary directly, greater than 16 generally converted to binary first, then to denary, using 4-bit binary numbers

Question 26

What is a media access control (MAC) address?

Answer 26

Unique address given to a computer at the manufacturing stage, used to identify the computer

Question 27

How does binary addition work?

Answer 27

Uses four rules: 0+0=0; 1+0=1; 1+1=10 (2 is 10 in binary); 1+1+1 = 11 (3 is 11 in binary)

Question 28

What is an overflow error?

Answer 28

A type of error which occurs when a number larger than what a register can store is generated

Question 29

What is a logical binary shift and what do they do?

Answer 29

Logical binary shift moves binary values in number to left or right; leftward shift doubles number, rightward shift halves number; some binary values removed and empty spaces created with each shift

Question 30

What is a potential problematic effect of a logical binary shift?

Answer 30

Vital bits can be removed from the register, therefore data can be lost. Consequently, leftward and rightward shifts don't always double and halve the number

Question 31

How is a negative number represented in binary?

Answer 31

Method of two's complement used; take positive number in binary, invert all values in binary (1s and 0s swapped); 1 added to result; outcome is binary representation of negative number using two's complement method

Question 32

How is text converted to binary?

Answer 32

Character set used like ASCII or Unicode, each character has binary value assigned to it

Question 33

What is a character set?

Answer 33

Contains all characters in the character set and binary value assigned to each character

Question 34

What are the two main types of character set and how do they work?

Answer 34

ASCII represents characters using 8-bit binary, can represent up to 256 characters; Unicode character set uses 16-bit binary, can represent approximately 65,000 characters

Question 35

How are images converted to binary?

Answer 35

Image made up of tiny dots called pixels, with colour. Each pixel has colour made using RGB colour system, with metadata like image dimensions allows computer to create image if given data for each pixel

Question 36

What is a pixel?

Answer 36

A very small dot of colour displayed with many others to create an image

Question 37

What is resolution?

Answer 37

The dimensions of an image

Question 38

What is metadata?

Answer 38

Additional data stored with image like dimensions of image, time and date image was taken

Question 39

What is colour depth?

Answer 39

The number of bits used to create each colour in an image

Question 40

How does resolution or colour depth affect the size of an image file?

Answer 40

If resolution or colour depth is increased, more data will be needed so file size is larger for the image

Question 41

How is sound converted to binary?

Answer 41

Sound sampling used to record little pieces of sound at regular time intervals, each sound value converted to binary, values then used to playback sounds, works due to sound being made up of sound waves

Question 42

What is sound sampling?

Answer 42

Little piece of sound recorded at regular time intervals

Question 43

What is sample rate?

Answer 43

The number of samples recorded each second

Question 44

What is sample resolution?

Answer 44

Number of bits used to record each sound sample

Question 45

How is recorded sound quality and file size affected by sample rate and sample resolution?

Answer 45

The higher sample rate and sample resolution, the greater the recorded sound quality is, but the greater the file size is as well due to more data being needed

Question 46

What is a common sample rate and sample resolution?

Answer 46

Sample rate - 44.1kHz, sample resolution - 16-bit

Question 47

What are the units of data measure?

Answer 47

Bit - smallest data measurement; nibble - 4 bits in nibble; byte - 8 bits in byte; kibibyte (KiB) - 1024 bytes; mebibyte (MiB) - 1024 kibibytes; gibibyte (GiB) - 1024 mebibytes; tebibyte (TiB) - 1024 gibibytes; pebibyte (PiB) - 1024 tebibytes; exbibyte (EiB) - 1024 pebibytes

Question 48

What is compression?

Answer 48

Method which uses an algorithm to reduce the size of a file

Question 49

What are the benefits of compression?

Answer 49

Not as much storage space needed for file; takes less time to transmit; quicker to upload and download; less bandwidth needed to transmit file over internet

Question 50

What are the 2 types of compression and how do they work?

Answer 50

Lossy - compression method which permanently removes data; lossless - compression method which temporarily alters data

Question 51

What does lossy compression do, where is it applied generally?

Answer 51

Permanently removes unnecessary data in file, mainly used on image or sound file

Question 52

What might lossy compression do on an image file?

Answer 52

Removes colours indistinguishable to human eye, reduces image resolution and colour depth

Question 53

What might lossy compression do on a sound file?

Answer 53

Removes sound unhearable by human ear, or sounds not heard due to other sounds, reduces sample rate and sample resolution

Question 54

What is perceptual music shaping?

Answer 54

Process used in lossy compression which finds and removes sounds not normally heard by human ear

Question 55

How does lossless compression work, and what can it be used on?

Answer 55

Common method used is finding repeating data and grouping it together, can be used on text file or on image file

Question 56

What is run length encoding (RLE)?

Answer 56

A lossless compression algorithm which groups together repeating patterns and indexes them, applied to image files