Zusammenfassung der Ressource
Key Terms
- Units
- Bit - A single binary digit: 1 or 0
- Byte - 8 Bits
- Nibble - 4 Bits
- Kilobyte - 1024 bytes
- Megabyte - 1024 Kilobytes
- Gigabyte - 1024 Megabytes
- Terabyte - 1024 Gigabytes
- Numbers
- Binary - Base 2 number
system, used by computers,
uses the digits 1 & 0 only.
- Denary - Base 10
number system,
how we normally
count, uses digits 0
to 9.
- Hexadecimal (Hex) - Base
16 number system used by
humans to represent groups
of four bits at a time. Uses
digits 0 to F.
- Overflow - When the result of a
numeric calculation is too large to be
stored in the space reserved for that
type of data.
- Characters
- Character set - The set of symbols that can be
represented by a computer. The symbols are
called characters and can be letters, digits,
space, punctuation marks and some control
characters such as “escape”. Each character is
represented by a numerical code that is stored
as a binary integer.
- ASCII - American Standard Code
for Information Interchange: a
7-bit character set used by PCs.
(There is also an extended ASCII
character set that uses 8 bits.)
- EBCDIC - Extended Binary Coded
Decimal Interchange Code: an 8-bit
character set used by older mainframes.
- Unicode - A 16-bit
character set that
allows many more
characters to be
coded.
- Images
- Bitmap image - An image that has been
stored as a series of values per pixel. The
colour of each individual pixel is stored in
a file.
- Vector Graphic - An image file that is made
up of lines and shapes that have certain
properties, for example, a line may have the
following properties: start- point, end-point,
line colour, line thickness, line style. The
properties of each shape are stored in a file
to make up the image.
- Pixel - Short for picture
element. It is the smallest
component of a
bit-mapped image.
- Colour depth - The number of bits used to
represent the colour of a single pixel in a
bitmapped image. Higher colour depth gives
a broader range of distinct colours. For
example, an image stored as a .gif file uses 8
bits per pixel so the image could use 256
different colours.
- Resolution - The number of pixels in an image
expressed as: the-number-of-pixels-across x
the-number-of-pixels-down eg: 400 x 600.
- Metadeta - Data about data. In the
case of image files metadata is the
data the computer needs to interpret
the image data in the file, for example:
resolution, colour depth and image
dimensions.
- Sound
- Analogue - A
continuously
changing
wave such as
natural
sound.
- Digital - Data that is made up of
separate values. How data is stored
on a computer.
- Sample rate - The number of times per
second that the sound wave is measured.
The higher the rate the more accurately
the sound wave is represented.
- Sample interval - The time gap
between measurements of the
sound wave being taken.
Another way of expressing the
sampling rate.
- Sample resolution - The number of bits
used to store the value of each sample.
The higher the number of bits the more
accurately the value is stored.
- ADC - Analogue to Digital
converter: takes real-world analogue
data and converts it to a binary
representation that can be stored
on a computer.
- Data and information
- Data - Facts and figures
with no context or format
to give them meaning.
- Information -
Processed data that
has context and
format so that it
conveys meaning.
- Instructions
- Instruction set - The group of instructions available for
that specific processor to use. The number of
instructions available will depend on the number of bits
used. For example, with 4 bits there could potentially be
15 different instructions.
- OP Code - The group of bits in an
instruction that represents the
operation such as EAT, MOVE or
TURN
- Compiler - A piece of systems software that
converts a program written in a high level
programming language into machine code
(binary).
- Machine code - A binary
representation of a program.
- High Level Programming Language - A programming
language written in constructs using language we can
understand. Languages include Delphi, Visual Basic,
Java and C++.