Memory and Storage 1.2 (2) Flashcards
What is a bit
A single binary digit
Dividing and multiplying in binary
Multi: Shift to left shift to right is divi
Divi: Shift to right
State hexadecimal terms
0-9 A-F
Why doesn’t hex go past 9
Because it won’t store one digit
Define Character set
Group of characters that a computer recognises from their binary representation
Why do programmers often prefer hex when coding ( 3 marks)
Easier to remember large numbers in hex as it is shorter than binary numbers
Because hex numbers are shorter there’s less chance of input errors
Its easier to convert between binary and hex than binary and denary
Each ASCII character is given a ..
this means it can..
7 bit binary code
represent a total of 128 characters
What is added to the start of the binary code for each ASCII character and why
an extra bit to fit nicely into 1 bit
What does Unicode try to do?
And what binary codes does it use
Cover every possible character that might be written
Uses 16 and 32 bit binary codes
What is the benefit of using Unicode
Covers all major languages
What is the most commonly used image format in a computer and how are pixels arranged
Bitmap, pixels arranged in a grid
How is colour of each pixel represented
binary code
How many bits does a black and white image use and coloured image use
1 bit - 0 white 1 black
2 bit - 00, 01,10,11
Define colour depth
The number of bits used for each pixel
What is resolution
The number of pixels in a certain section of a bitmap image and is usually measured in dpi
Equation for file size
File size = sample rate x bit depth x length (seconds)
What are sampling intervals
The gaps between where an analogue recording is sampled
What is bit rate
Number of bits that are available for each sample
Two things that Metadata can store
Time of photograph
Where image was taken
Pros cons lossy and examples
pros : Takes up less bandwidth so can be downloaded and streamed more quickly
Commonly used - lots of software can read lossy files
Cons Can’t be used on text or software files
Can’t turn back to original
MP3
AAC
JPEG
Pros cons lossless and examples
Pros : data only removed temporarily no reduction in quality
lossless files can be decompressed and turn back to original
Can be used on text and software files
Cons : file size is not reduced greatly
FLAAC
TIFF PNG
