Computer systems Flashcards
what does decimal or denary mean
numbers written in base 10 using the digits 0 - 9
what does binary mean
means numbers are written in base 2 using the digits 0 - 1
why do computer systems use binary numbers to encode all info
its electronically easier to represent only two values
it is easier to build electronic circuitry for carrying out calculations with only two numbers
the advances in hardware mean its possible to store and process large quantities of digital info.
How does a computer system know what 10000010100101000100010110010001 represents?
It depends largely on what the computer is expecting! Each piece of data will carry a code indicating what type
of data it is
what is an integer
a number with no fractional part e.g. 76, 2
what is 73 in binary
01001001
what is 10011100 in decimal
156
whats the largest possible 8 bit binary number
11111111 - 255 = 2’8
– 1)
what is a real number
a number that has a fractional part
how is a real number stored
using floating point representation using a mantissa and an exponent e.g. 6527.802 = 0.6527802 x 104
what is a character
– any symbol or letter found on a keyboard. Each character has a unique numerical value inside
the computer e.g. ‘A’ is 01000001 (= 65).
what is a computer character set
a list of all characters a computer can process and store. Different
computers have different character sets
what are control characters
do not print on the screen in the normal way. They control certain operations of the
computer such as ‘cursor up’, cursor down’, ‘clear screen’, ‘tab’, ‘return (enter)’, ‘delete’ etc. If you look at
the table below, they are characters with ASCII codes 0 to 31
what is extended ASCII
american standard code for information interchange
its stored using one byte (8bits)
2’8 = 256 therefore ASCII can represent 256 different characters
In ASCII, codes 0 - 31 are used for control characters e.g. 0001001 is the tab key
what are vector graphics
graphics made up of objects each having a set of attributes
give examples of some vector graphic objects
rectangle, ellipse, line, polygon
give examples of vector attributes
co-ordinates, fill colour, line colour
what happens to vector graphic files as the complexity of the graphic increases
the file size increases
what are bitmap graphics
bitmap graphic are graphics made up by pixels
what are pixels
picture elements
explain black and white bitmapped graphics
one bit per pixel (0 for white, 1 for black)
number of bits = no of pixels
what is a bitmap
a grid of bits (1s and 0s) is used to represent the colour of the pixels of the graphic.
explain colour bit mapped graphics
Several bits are assigned to each pixel to represent the colour of the pixel
- e.g. 10 bits per pixel means 1024 possible colours for each pixel
- True colour means 24 bits per pixel (the limit at which the human eye can distinguish between colours).
This gives a total range of 16777216 colours
what is the resolution of a graphic
the no of pixels making up the graphics
determines the quality of the graphic
the smaller the pixels the higher the resolution of 8 mega pixels
