Data Storage & Compression (OCR GCSE Computer Science)
Flashcards
1/1260Still learning
Know0
Define units of data.
Enjoying Flashcards?
Tell us what you think
Cards in this collection (126)
Define units of data.
Units of data is a term describing different amounts of binary digits stored on a digital device.
Define bit.
A bit is the smallest unit of data a computer can store, represented as 1 or 0.
Define nibble.
A nibble is a group of 4 bits.
Define byte.
A byte is comprised of 8 bits and can represent a single character.
Define kilobyte (KB).
A Kilobyte is 1000 bytes, equivalent to 2^10 bytes.
Define megabyte (MB).
A Megabyte is 1000 Kilobytes or 1,000,000 bytes, equivalent to 2^20 bytes.
Define gigabyte (GB).
A gigabyte is 1000 Megabytes or 1,000,000,000 bytes, equivalent to 2^30 bytes.
Define terabyte (TB).
A terabyte is 1000 Gigabytes or 1,000,000,000,000 bytes, equivalent to 2^40 bytes.
Define petabyte (PB).
A petabyte is 1000 Terabytes or 1,000,000,000,000,000 bytes, equivalent to 2^50 bytes.
What is the process for converting between different units of data?
Conversion involves division when moving up to larger units and multiplication when moving down to smaller units.
True or False?
When converting between units bigger than a byte, multiples of 1000 are used.
True.
When converting between units bigger than a byte, multiples of 1000 are used.
True or False?
There are 8 bits in a byte.
True.
There are 8 bits in a byte.
Why does data have to be converted to binary to be processed by a computer?
Data has to be converted to binary to be processed by a computer because computers are built using switches that can either be on or off, which fits the binary number system (1/0).
Define binary data.
Binary data is data represented using the binary number system, consisting of only two digits: 1 and 0.
Why do computers use binary?
Computers are built using circuits and transistors. The circuits only need to check for two states:
On / off
True / False
North / south
1 / 0
Define binary number system.
The binary number system is a base-2 number system that represents numbers using only two digits: 0 and 1.
What is an example of binary representation in secondary storage devices?
An example of binary representation in secondary storage devices is magnetic hard drives, where North and South polarity represent 1 and 0.
Define transistor.
A transistor is a semiconductor device used to amplify or switch electronic signals and electrical power.
What is the advantage of processing data in binary format for computers?
Processing data in binary format allows computers to perform complex calculations, store vast amounts of data efficiently, and operate at incredible speeds.
Define secondary storage.
Secondary storage refers to non-volatile storage devices that retain data even when the computer is turned off, such as hard drives and optical disks.
What is data capacity?
Data capacity is the maximum amount of information that a storage device can hold.
True or False?
Data capacity is the same as file size.
False.
Data capacity refers to the maximum storage capacity of a device, while file size refers to the amount of storage used by a specific file.
What do you need to know to calculate capacity requirements?
To calculate capacity requirements, you need to know:
the capacity of the storage device
the size of the file(s) being stored.
State the equation for calculating the size of a text file.
Size of text file = (Bytes per character) x (Number of characters)
What is the equation for calculating the size of an image file?
Size of image file = (Resolution) x (Colour Depth)
Define resolution.
Resolution is the total amount of pixels that make up a bitmap image, calculated by multiplying the height and width of the image (in pixels).
What is colour depth?
Colour depth is the number of bits stored per pixel in a bitmap image.
State the equation for calculating the size of a sound file.
Size of sound file = (Sample Rate) x (Duration in seconds) x (Bit Depth)
Define sample rate.
Sample rate is the amount of samples taken per second of an analogue sound wave.
What is bit depth in the context of sound?
Bit depth is the number of bits stored per sample of sound.
What is denary?
Denary is a number system that is made up of 10 digits (0-9), also known as the Base-10 number system.
True or False?
Humans use the binary system for counting and performing math calculations.
False.
Humans use the denary system for counting, measuring, and performing math calculations.
Define binary.
Binary is a number system that is made up of two digits (1 and 0), also known as the Base-2 number system.
Why do computers use binary?
Computers use binary numbers to represent data because they are built using transistors that can only be in a state of on or off, which fits the binary number system of 1s and 0s.
True or False?
At GCSE level, you will be asked to convert from/to binary up to and including 16 binary digits.
False.
At GCSE level, you will only be asked to convert from/to binary up to and including 8 binary digits (8 bits).
What is the denary range you will work with when converting to/from binary at GCSE level?
At GCSE level, you will work with a denary range of 0-255 (00000000-11111111 in binary).
Convert the following binary number to denary.
128
64
32
16
8
4
2
1
1
0
1
0
1
1
0
0
128+0+32+0+8+4+0+0=172
Convert the following binary number to denary.
128
64
32
16
8
4
2
1
0
1
1
1
0
0
0
1
0+64+32+16+0+0+0+1=113
Convert the following binary number to denary.
128
64
32
16
8
4
2
1
1
0
0
1
0
0
0
0
128+0+0+16+0+0+0+0=144
Convert 76 to binary.
128
64
32
16
8
4
2
1
0
1
0
0
1
1
0
0
Convert 150 to binary.
128
64
32
16
8
4
2
1
1
0
0
1
0
1
1
0
Convert 94 to binary.
128
64
32
16
8
4
2
1
0
1
0
1
1
1
1
0
What is binary addition?
Binary addition is the process of adding together two binary integers (up to and including 8 bits).
True or False?
Binary addition starts from the rightmost digit and moves left.
True.
Binary addition starts from the rightmost digit and moves left.
What does "carrying over" mean in binary addition?
Carrying over occurs when the sum of a column is greater than 1, passing the excess to the next left column.
Define overflow error.
An overflow error is when the result of a binary addition exceeds the available bits.
What is 1 + 1 in binary addition?
1 + 1 = 10 (2 in denary)
True or False?
The sum of 1001 and 0100 in binary is 1101.
True.
The sum of 1001 and 0100 in binary is 1101.
What is the sum of 00011001 and 10000100 in binary?
The sum of 00011001 and 10000100 in binary is 10011101.
Define binary integer.
A binary integer is a number represented in the base 2 number system.
Perform the following binary addition
128
64
32
16
8
4
2
1
0
0
0
1
1
0
1
1
0
1
1
0
0
1
0
1
128
64
32
16
8
4
2
1
0
0
0
1
1
0
1
1
0
1
1
0
0
1
0
1
1
1
1
1
1
1
1
1
0
0
0
0
0
0
0
Perform the following binary addition
128
64
32
16
8
4
2
1
1
1
1
1
0
0
0
0
0
0
0
0
1
1
1
1
128
64
32
16
8
4
2
1
1
1
1
1
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
1
1
1
1
Perform the following binary addition
128
64
32
16
8
4
2
1
0
1
0
1
0
1
1
0
0
0
0
0
1
1
1
1
128
64
32
16
8
4
2
1
0
1
0
1
0
1
1
0
0
0
0
0
1
1
1
1
1
1
1
1
0
1
1
0
0
1
0
1
What is hexadecimal?
Hexadecimal is a number system with 16 digits.
True or False?
Hexadecimal uses 16 digits.
True.
Hexadecimal uses 16 digits.
What is the relationship between hexadecimal and a binary nibble?
One hexadecimal digit represents four bits of binary data.
Define nibble.
A nibble is four bits of binary data or half a byte.
What is the non-mathematical method for converting denary to hexadecimal?
Convert denary to binary, split into nibbles, then convert each nibble to hexadecimal.
What is the mathematical method for converting denary to hexadecimal?
Divide denary by 16 and record the whole times (hex digit 1) and remainder (hex digit 2).
Example: Denary 160 to Hexadecimal = 160/16 = 10 (A) r 0 = A0
What is the non-mathematical method for converting hexadecimal to denary?
Convert each hexadecimal digit to 4-bit binary, join nibbles, then convert binary to denary.
What is the mathematical method for converting hexadecimal to denary?
Multiply the first digit by 16, then add the second digit.
Example: Hexadecimal B4 to denary = B (11) x 16 = 176 + 4 = 180
Convert denary 45 to hexadecimal.
Convert 45 to binary
128
64
32
16
8
4
2
1
0
0
1
0
1
1
0
1
Split in to 2 nibbles (4-bits)
0010 = 2
1101 = 13 (D)
Answer = 2DConvert hexadecimal E7 to denary.
Convert each digit to 4-bit binary (nibble)
8
4
2
1
1
1
1
0
8
4
2
1
0
1
1
1
Combine to create an 8-bit value and convert to denary
11100111 = 231Define nibble.
A nibble is a group of four bits.
What is the definition of binary?
Binary is a base-2 number system that uses only 0 and 1 to represent all values.
True or False?
Each digit in a hexadecimal number represents a binary nibble.
True.
Each digit in a hexadecimal number represents a binary nibble.
Define denary.
Denary is the base-10 number system, which uses digits from 0 to 9.
What does hexadecimal mean?
Hexadecimal is a base-16 number system that uses 16 digits: 0-9 and A-F.
State the method in terms of X for converting binary to hexadecimal.
Method:
Split X (binary number) into 2 x nibbles (4-bits)
Convert each nibble to its denary value
Represent each denary value as a hexadecimal digit.
Example: 11011001 = 1101 (13=D), 1001 (9) = D9
True or False?
To convert hexadecimal to binary, you split the digits apart and convert each to a binary nibble.
True.
To convert hexadecimal to binary, you split the digits apart and convert each to a binary nibble.
What is the definition of bit?
A bit is a basic unit of information in computing, representing either a 0 or 1.
Define byte.
A byte is a unit of digital information that consists of 8 bits.
Convert binary to hexadecimal.
128
64
32
16
8
4
2
1
1
1
1
0
1
0
0
0
Split in to 2 nibbles (4-bits)
8
4
2
1
1
1
1
0
8
4
2
1
1
0
0
0
1110 = 14 (E)
1000 = 8
Answer = E8Convert hexadecimal 4B to binary.
Convert each digit to a 4-bit binary value
8
4
2
1
0
1
0
0
8
4
2
1
1
0
1
1
Combine to create an 8-bit value
Answer = 01001011Define binary shift.
A binary shift is how a computer system performs basic multiplication and division by moving binary digits left or right a set number of times.
What does a left shift do?
A left shift multiplies a binary number by 2 (for every 1 place shift).
True or False?
A right shift divides a binary number by 2.
True.
A right shift divides a binary number by 2 (for every 1 place shift).
What is the definition of overflow error?
An overflow error occurs when a result is too large to be represented in the available storage space (needs more bits).
Define underflow error.
An underflow error occurs when a result is too small to be represented in the available storage space.
State the equation in terms of X for a left shift of 2 places.
X << 2 (X shifted left by 2 places) = X * 4
True or False?
A left shift of 3 places multiplies the binary number by 8.
True.
A left shift of 3 places multiplies the binary number by 8.
In binary shifts, what is the definition of precision?
In binary shifts, precision refers to the number of digits used to represent a value.
Define bit.
A bit is a basic unit of information in computing, representing either a 0 or 1.
What does binary multiplication mean?
Binary multiplication refers to the process of multiplying binary numbers using shifts and additions.
Define character set.
A character set is a defined list of characters that can be understood by a computer, where each character is given a unique binary code.
What is ASCII?
ASCII (American Standard Code for Information Interchange) is a character set that uses 7 bits, allowing it to represent a maximum of 128 characters.
True or False?
ASCII can represent characters from all major languages around the world.
False.
ASCII can only represent basic characters needed for English, limiting its use for other languages.
What is the definition of extended ASCII?
Extended ASCII is a character set that uses 8 bits, allowing it to represent a maximum of 256 characters.
Define UNICODE.
UNICODE is a character set that uses a minimum of 16 bits, allowing it to represent a minimum of 65,536 characters from all major languages around the world.
State the meaning of bit.
A bit is a single binary digit, representing either a 0 or 1.
True or False?
UNICODE uses more storage space than ASCII.
True.
UNICODE uses more storage space than ASCII because it uses more bits to represent characters.
What does character encoding mean?
Character encoding refers to the process of assigning a unique binary code to each character in a character set.
True or False.
A drawback of ASCII is that it cannot represent special characters such as emoji's?
True.
A drawback of ASCII is that it cannot represent special characters such as emoji's (not enough bits)
What is the equation in terms of X for the maximum number of characters in a character set using X bits?
Maximum number of characters =
(to the power of the number of bits)Define bitmap.
A bitmap is an image made up of squares called pixels, where each pixel is stored as a binary code.
What is a pixel?
A pixel is the smallest element of a bitmap image.
True or False?
A vector image is created from mathematical equations and points.
True.
A vector image is created from mathematical equations and points.
Define resolution.
Resolution is the total amount of pixels that make up a bitmap image, calculated by multiplying the height and width of the image (in pixels).
What does colour depth mean?
Colour depth is the number of bits stored per pixel in a bitmap image.
State the equation in terms of X for the maximum number of colours in an image with colour depth X.
Maximum number of colours =
(2 to the power colour depth)Example: Colour depth = 8, 28 = 256 colours
True or False?
Higher resolution and colour depth result in larger file sizes.
True.
Higher resolution and colour depth result in larger file sizes.
What is the definition of metadata?
Metadata is data about data, or additional information stored with an image but not required to display the image.
True or False.
An advantage of vector images is they are scalable?
True.
A vector image is scalable, it is able to be resized or changed in size without loss of quality.
True or False?
A vector image is made up of pixels.
False.
A vector image is created from mathematical equations and points, not pixels.
What is the meaning of True Colour?
True Colour refers to a colour depth of 24 bits, allowing for 16,777,216 colours.
Define pixel depth.
Pixel depth is another term for colour depth, referring to the number of bits used to represent the colour of each pixel.
Define sampling.
Sampling is the process of measuring and capturing values of an analogue signal at regular intervals.
What is an analogue signal?
An analogue signal is a continuous signal that can take on any value within a range, such as a sound wave.
True or False?
Sound must be converted from analogue to digital form for a computer to process it.
True.
Sound must be converted from analogue to digital form for a computer to process it.
What does Analogue to Digital conversion (A2D) mean?
Analogue to Digital conversion (A2D) is the process of converting an analogue signal, such as sound, into a digital form that a computer can understand.
Define sample rate.
Sample rate is the amount of samples taken per second of an analogue signal, measured in Hertz (Hz).
State the meaning of bit depth.
Bit depth is the number of bits stored per sample of sound.
True or False?
Higher sample rate and bit depth result in better sound quality but larger file sizes.
True.
Higher sample rate and bit depth result in better sound quality but larger file sizes.
What is the definition of Hertz (Hz)?
Hertz (Hz) is the unit of measurement for frequency, equal to one cycle per second.
What does amplitude mean in the context of sound waves?
Amplitude refers to the height of a sound wave.
True or False?
The sample rate of a typical audio CD is 44.1 kHz (44,100 samples per second).
True.
The sample rate of a typical audio CD is 44.1 kHz (44,100 samples per second).
What is the definition of digital?
Digital refers to data represented as a series of discrete values, typically 0s and 1s in binary.
Define duration.
Duration is the length of time that something lasts, in the context of sound, it refers to the length of the recorded audio.
Define compression.
Compression is reducing the size of a file so that it takes up less space on secondary storage.
What is lossy compression?
Lossy compression is when data is lost in order to reduce the size of a file on secondary storage.
True or False?
Lossy compression is irreversible.
True.
Lossy compression is irreversible.
What does irreversible mean?
Irreversible means something that cannot be undone or reversed to its original state.
Define lossless compression.
Lossless compression is when data is encoded in order to reduce the size of a file on secondary storage.
True or False?
Lossless compression can be used on all data types without losing quality.
True.
Lossless compression can be used on all data types without losing quality.
Define encoding.
Encoding is the process of converting data into a specific format or code.
True or False?
Lossy compression can greatly reduce file size but at the expense of losing quality.
True.
Lossy compression can greatly reduce file size but at the expense of losing quality.