2.3.2 Architecture 2 Flashcards
Primary storage
Memory
Secondary storage
Name given to any device used to hold permanent copy of - save work
- operating system
- programmes
- data
The need for secondary storage
Memory volatile
Then results of processing not stored there
Types of secondary storage
Magnetic
Optical
Flash
ROM
Used to permanently store basic I/o system
- instructions used to power up device and load operating system
RAM
Main memory
- temporarily store operating system, programmes and data being used
CACHE
Form of memory that can be r/w to
High speed volatile memory
Located in CPU
store copies of contents- most frequently used memory locations.
Searched by CPU before main memory.
Enables CPU to process instructions faster.
Magnetic storage media
Data stores as magnetically aligned particles on…
- a read/ write head- platters
How Can magnetic storage media read or write particles by
- moving to the correct sector of the platters which are constantly moving.
- and applying a magnetic force to the particles
- when a programme is loaded or a file opened the 1s and 0s are read and copied into the memory
- the permanent copy remains on the hard disk
- when a file is saved the results of processing are copied from memory and written in a pattern of particles on the sectors and tracks of a hard drive platter.
FLASH
- data is stored electronically on silicon based microchips.
- look very different to RAM memory chips
- transistors contain an extra part that allows for the input/ output kept in transistor to be stored when no power.
- each FLASH device wiped at higher voltage required
- cannot r/w to I definitely.
Typical optical storage media
CD-ROM CDR CDRW DVD BLU RAY
CD-ROM
700mb
CDR AND CDRW
700mb
DVD
4.7gb
Smaller light wavelength used= more circles can fit in
Dual layer DVDs used 2 layers on top of each other.
BLU RAY
25gb
Blue light shorter wavelength than red
Used for HD storage media storage.