memory and storage Flashcards
what is RAM
its a temporary memory and is used to store data, programs or parts of the operating system. It can be read or written from
what is ROM
its a permanent memory and is used to store start-up procedures or basic input/output system. It can only be read and not written from
what is DRAM
it needs to constantly refreshed to retain the data. It uses millions of transistors and capacitors
what is SRAM
doesn’t need to be constantly refreshed to retain the data. It uses flip flops
what are the adv of DRAM over SRAM
they are inexpensive
they can store many bits per chip
uses less power
generates less heat
what are the adv of SRAM over DRAM
faster than DRAM
cannot store many bit per chip
what are DRAM used for
main memory
what are SRAM used for
used for cache
what is PROM
it can be programmed by the user. Once programmed, the data in it cannot be changed
what is EPROM
it can be reprogrammed. Exposing it to ultraviolet light will erase the data
what is EEPROM
the data can be erased by applying electric field - can only erase a portion of the chip
how does HDD (hard disk drive) work
- uses platters
- platters are divided into tracks
- platter is spun
- read write arm moves over the platter
- magnetic fields control the magnetic dots of data
- magnetic field determines the binary value
what is SSD (solid state drive)
its a permanent memory and uses NAND flash memory
what are some reasons for why SSD is replacing HDD
more reliable and smaller in portable devices as theres no moving parts
uses less power so it runs cooler and runs quieter
faster data access
why is HDD still used in web servers
it is cheaper for large amounts of data
web servers don’t need faster speed of SSD
it is expensive to change technology to SSD
