1.2 - storage and binary Flashcards
What is primary storage
RAM and ROM, storage on the motherboard
What is RAM
random access memory, stores currently running programs, volatile
What is ROM
bootstrap (start up) information, non-volatile, OS
What is virtual memory
when part of secondary storage is used as primary storage (allows to run bigger programs, slower)
What is secondary storage
Non volatile storage not on the motherboard
what are the three main types of secondary storage and how do they work
Optical - light reflected or not, portable
Magnetic - magnetised or not, cheaper
SSD (solid state) - transistor on or off, faster, smaller
Why do computers use digital electronics (on or off, binary)
To stop information being lost by interference
How do you add binary
0+0=0, 1+0=1, 1+1= 0 carry 1
what is an overflow error
when a number becomes too large to represent with 8 bits
how do you convert binary to denary
rightmost bit is 1, then 2, 4, 8, 16 ect. Then add them up
How do you multiply or divide binary
to x by 2 you shift the number left one, to / by 2 you shift the number right one.
how do you convert hex to binary
convert each digit into 4 bit binary number, then put them together
What is a pixel
a single square on a screen that can be coloured
What is metadata
the information about a picture that isn’t colour e.g. width and height, location, time created
What is colour depth
The number of bits per pixel in an image (number of colours)
What is the resolution of an image
number of pixels per cm
how do you calculate image file size
height x width x colour depth x resolution
What is sampling rate
How many samples of a sound wave you make per second
what is bit depth of a sound
how many bits are used to represent the height (amplitude) of a sound wave
how do you calculate sound file size
sampling rate x bit depth x duration
what is a character set
a list of binary numbers which represent a character (e.g. letters and numbers)
what is the difference between AsCii and unicode
ascii uses 7 bits so can only write 127 symbols, unicode has more
why is compression needed
to save storage space and reduce file upload and download times
what is the difference between lossy and lossless compression
lossy compression is where files are compressed a lot but some information is lost, lossless compression compresses the file less but no information is lost
