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
easier to represent only two values
it is easier to build electronic circuitry for carrying out calculations with only two numbers
its possible to store and process large quantities of digital info in this form
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 typeof data it is
what is an integer
a number with no fractional part e.g. 76, 2
whats the largest possible 8 bit binary number
11111111 (255)
OR 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.
what is a computer character set
a list of all the 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 thecomputer
cursor up’, cursor down’, ‘clear screen’, ‘tab’, ‘return (enter)’, ‘delete’ etc. they are characters with ASCII codes 0 to 31
what is extended ASCII
american standard code for information interchangeits stored using one byte (8bits)2’8 = 256 therefore ASCII can represent 256 different charactersIn 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 graphicsdetermines the quality of the graphic the smaller the pixels the higher the resolution
what is bit depth
The greater the number of bits usedfor each pixel, the greater the variety of colours)
how many bits would 128 colors require
128 = 2’7so 7 bits required
What is the bit depth of a graphic allowing up to 1024 colours?
Ans: 1024 = 2’10 therefore bit depth = 10
does changing the colours in a bitmapped graphic alter the storage requirement
no
If the bit depth orresolution of a bit-mapped graphic changed would the file size change
yes
As bit depth and resolution increases what will happen
the quality of the image will increase but the file size will too,
what happens when two shapes overlap in bit mapped graphics
the shape on top will “rub out”
what happens when two shapes overlap in vector graphic
individual objects can be selected and layered
what type of graphic can you edit at pixel level
bit mapped graphics
.
.
what happens to a vector graphic file size
it increases asobjects are added
what is the ALU
Arithmetic logic unit
what does the ALU do
carries out calculations and makes decisions and logical operations
whats the control unit
controls all the parts of the processor and makes sure that the program instructions are synchronized to be executed in the correct order
whats the register
Registers are storage locations inside the processor chip that hold data while the processor is using it
Whats the MAR
Memory Address Register.
what does the MAR do
holds the address of the data in memory that is currently beingaccessed
whats the MDR
memory data register
what does the MDR do
holds the contents of the data currently being accessed
