IGCSE COMPUTER SCIENCE - 1.1 DATA
REPRESENTATION EXAM QUESTIONS
AND ANSWERS
Synthesis - Answer-The process of creating the sound from an audio file.
Sample frequency - Answer-How many sound samples are taken per second. This is
measured in hertz (Hz). The higher the sample frequency the more samples are taken
per second and the more like the original sound it will be when played back.
Compression - Answer-A process that results in needing less storage space (bytes) to
store some data.
Lossy compression - Answer-A compression method that would make it impossible to
derive the original data. Common methods are the JPEG image format and the MP3
audio format.
Lossless compression - Answer-A compression method the means you can derive an
exact copy of the original data. Methods include FLAC for audio files and PNG for
images.
Overflow - Answer-When the result of a process (such as adding two bytes) is too big to
fit in the allocated storage space. Adding two lots of 8 bits could result in a 9 bit answer
for example and this would not fit in a single 8 bit byte.
Meta Data - Answer-Data about data. The meta data on an image file will describe the
colour depth and the dimensions of the image. The meta data on an audio file will
describe the sample resolution and the sample rate.
Pixelation - Answer-When a bit map image is enlarged so much that you can see the
individual pixels.
Machine code
1st Generation language - Answer-The 1s and 0s that make up the instructions for a
computer. This is the lowest level of programming language that all programs must be
converted to in order to be executed on a computer. Computers only understand
machine code.
Assembly language
2nd generation language - Answer-One step up from machine code where the individual
machine code instructions are represented as simple keywords such as ADD or BRA.
Requires an assembler to turn it into machine code.
REPRESENTATION EXAM QUESTIONS
AND ANSWERS
Synthesis - Answer-The process of creating the sound from an audio file.
Sample frequency - Answer-How many sound samples are taken per second. This is
measured in hertz (Hz). The higher the sample frequency the more samples are taken
per second and the more like the original sound it will be when played back.
Compression - Answer-A process that results in needing less storage space (bytes) to
store some data.
Lossy compression - Answer-A compression method that would make it impossible to
derive the original data. Common methods are the JPEG image format and the MP3
audio format.
Lossless compression - Answer-A compression method the means you can derive an
exact copy of the original data. Methods include FLAC for audio files and PNG for
images.
Overflow - Answer-When the result of a process (such as adding two bytes) is too big to
fit in the allocated storage space. Adding two lots of 8 bits could result in a 9 bit answer
for example and this would not fit in a single 8 bit byte.
Meta Data - Answer-Data about data. The meta data on an image file will describe the
colour depth and the dimensions of the image. The meta data on an audio file will
describe the sample resolution and the sample rate.
Pixelation - Answer-When a bit map image is enlarged so much that you can see the
individual pixels.
Machine code
1st Generation language - Answer-The 1s and 0s that make up the instructions for a
computer. This is the lowest level of programming language that all programs must be
converted to in order to be executed on a computer. Computers only understand
machine code.
Assembly language
2nd generation language - Answer-One step up from machine code where the individual
machine code instructions are represented as simple keywords such as ADD or BRA.
Requires an assembler to turn it into machine code.
