iGCSE Computer Science - 1.1 Data Representation
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. Computer...
iGCSE Computer Science - 1.1 Data
Representation
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.
High level language
3rd generation language. - Answer- A computer programming language that is much closer to a human language than
machine code. Examples of high level languages are Python, PHP, Visual Basic and C (although there are lots more!).
Requires and interpreter or a compiler to turn it into machine code.
Bit - Answer- A single binary digit. A bit will be either a 1 or a 0.
Nibble - Answer- 4 bits is equivalent to a single hexadecimal digit.
e.g. 0111 = 7, 1010 = A, 1111 = F
Byte - Answer- 8 bits. Can be used to represent any denary number from 0 to 255 (that's 256 different combinations!).
Kilobyte - Answer- 1024 or 2^10 bytes.
Megabyte (Mb) - Answer- 1024 kilobytes.
Gigabyte (Gb) - Answer- 1024 megabytes.
Terabyte (Tb) - Answer- 1024 gigabytes.
Binary - Answer- The number system we use to represent the data stored in a digital computer. Binary is a base 2 number
system and uses the digits 1 and 0.
Hexadecimal - Answer- A base 16 number system that we use to represent the data stored in a digital computer.
Hexadecimal is used instead of binary for two reasons: 1. It it easier for humans to read than binary. 2. A single hexadecimal
digit can be represented in a nibble (4 bits).
Bitmap - Answer- A method of representing images where a picture is divided up into a grid of pixels. Each pixel is stored
as a number which represents its colour.
Colour depth - Answer- The term used to describe the number of colours that can be stored in a bitmap image. This is
usually described as the number of bits set aside for each pixel. For example 8 bit colour depth can store 256 different
colours.
Sample resolution - Answer- The number of bits used to store each sound sample in an audio file. The more bits that are
used for each sample the higher the sample resolution and the more like the original sound it will be when played back.
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.
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