1.2- Memory And Storage Flashcards
need for primary storage
The memory areas that the CPU can access very quickly. It has the fastest read/write speeds and mostly volatile.
RAM
-used as the main memory which can be read and written to
-stores the operating system and data currently in use from secondary storage
-volatile
-high speed
-any part of it can be accessed any time at the same speed (random)
-slower than cache, but faster than secondary storage
ROM
-used to store the BIOS and bootstrap loader to boot up the computer
-non-volatile
-can only be read, not written to
-very small capacity compared to RAM
why is virtual memory needed
-when RAM is full the computer needs somewhere else to put application data
-too many applications open
-memory-intensive application being used
how virtual memory works
-moves data that hasn’t been used recently to virtual memory on secondary storage
-has to be moved back to RAM before the CPU can read it (slow)
disk thrashing
if the memory is very slow the computer has to swap data in and out
volatile memory
temporary, requires power to retain its data
non-volatile memory
permanent, keeps its contents when there’s no power
more RAM
more applications can be run smoothly so it works faster
secondary storage
-non-volatile
-where all data is stored when not in use
-slower read-write speeds to primary
magnetic storage
-mechanical parts move over the disks surface to read and write data magnetically
-often used by large organisations to store huge amounts of data
optical storage
lasers read and write data using light
solid state storage
-data is recorded onto solid memory chips without any moving parts
-use a type of flash memory
HDDs advantages
-low cost per GB
-reliable
-higher capacity then SSDs
-longer read/write life than SSDs
SSDs advantages
-faster read/write operations
-reliable
-more shock-proof than HDDs
-silent
optical disk advantages
-very cheap per GB
-portable
-not easily damaged by water or shocks (can be scratched)
optical disk disadvantages
-low capacity
-slow read/write speeds
-poor reliability
magnetic advantages
-much greater storage capacity than HDDs
-low cost per GB
-fast read/write speed
magnetic disadvantages
slow to find specific data stored on it
average read/write speed
1.SSD
2.HDD
3.magnetic
4.Optical
average cost per GB
1.magnetic
2.optical
3.HDD
4.SSD
average capacity
1.magnetic
2.HDD
3.SSD
4.optical
