Memory and Storage Finished Flashcards
What is memory
The component of the computer that holds data, programs and instructions that are currently in use
What is primary memory
Memory built into the computer that allows it to be read quickly
What are the two types of primary memory
Read only memory (ROM)
Random access memory (RAM)
Which type of primary memory is volatile
RAM
What does volatile mean
It will lose its memory when the computer is turned off
What is the standard size of primary memory
4 GB
What are the properties of ROM (3)
Can be read from
Cannot be edited
Contents are not lost when the computer is turned off
What does BIOS stand for
Basic Input Output System
What does the BIOS do
Checks the hardware is functioning correctly
Runs the bootup program that loads the computer’s operating system
What is RAM used for
To hold data and instructions that are currently in use
What is virtual memory
The use of secondary storage as additional primary memory
What happens when there isn’t enough RAM to hold all running programs
Part of the computer’s secondary storage is used to temporarily hold data
What is swapping
When unused data that has been transferred to the hard disk is needed again, it will swap that data for some of the data in RAM
Why is using virtual memory slower
The processor has to wait while data is swapped between hard disk and RAM
What is cache memory
A type of high-speed RAM which is built into the processor
What is cache used for
Holding data and instructions temporarily that the processor is likely to reuse
Why is the amount of cache in a computer small
It is very expensive
What are the two types of cache and what do they do
L1 cache - extremely fast transfer rates, very small. Used by the processor to hold the most frequently used data and instructions
L2 cache - Bigger than L1 but slower. Used to hold data and instructions that are used less frequently
What is flash memory
A special type of memory that can be written to and overwritten but is non-volatile
What are the advantages of flash memory (3)
Fast to access and write to, although not as fast as RAM
Requires little power
Contains no moving parts
What is flash memory used for (2)
Memory in devices such as tablets, smartphones and cameras
External secondary storage, such as USB memory sticks
What is secondary storage used for
Holding programs and data indefinitely
What are the characteristics of a hard disk drive (2)
High capacity
Reasonable access speed
What are the characteristics of a USB stick (3)
Smaller in capacity
Extremely fast
Portable
What are the types of secondary storage (3)
Magnetic - hard disk drives
Optical - CD, DVD, Blu-ray
Solid state - USB drives
How do magnetic devices work
Magnetic fields magnetise tiny sections of a metal spinning disk to represent binary
How is a magnetic device written to/read from
A read/write head moves across its surface while it’s spinning. To write, it magnetises, to read, it makes a not of if the section is magnetised or not
What are the advantages of magnetic storage (3)
Cheap
High in capacity
Durable
What are the disadvantages of magnetic storage (2)
Susceptible to damage if dropped
Vulnerable to strong magnetic fields
How are optical disks read from
A laser scans the surface of a spinning disk made of plastic and metal to look for tracks which are divided into flat areas (lands) and hollow areas (pits). When the laser shines on the disc lands will reflect light and represent a 1 and pits will scatter the light and represent a 0
What are the types of optical storage media and what are their characteristics (3)
ROM media - has data pre-written on them and cannot be overwritten
R media - a blank optical device that can be written to only once. It works by having a laser burn pits in the disc to represent 0s
RW media - similar to R, but can be written to more than once
How do solid state devices work
They use non-volatile RAM to store data indefinitely
What are the advantages of solid state devices (4)
Fast access time
Durable due to no moving parts
Require little power
Portable
What are the disadvantages of solid state devices
Expensive
What are the factors of secondary storage that should be taken into account (6)
Cost per GB Capacity Speed of access Portability Durability Reliability
