3.3 Data storage Flashcards
What are the 2 types of memory
Primary
Secondary
What memory comes under primary
ROM
RAM
Cache
2 Types of secondary and what comes under them
Internal - HDD, SSD
External - DVDs/CD, Blu ray disc, USB memory stick, Removable hard drive.
Differences between primary and secondary storage
Primary:
Can be directly accessed by CPU
Only internal
Secondary:
Not directly accessed by CPU
Non volatile memory
Can be external or internal
What does the primary memory allow the cpu/computer to do
Primary memory allows the CPU to access applications and services temporarily stored
What is volatile memory
Contents of memory are lost when the computer is powered off
What is non volatile memory
Contents of memory aren’t lost when the computer is powered off.
Process of running a program from secondary storage
When you run an application or program data is retrieved from secondary storage and placed
temporarily into RAM
Features of RAM
Can be read from or written to
Stores data, files, programs, parts of the OS that are currently in use
Volatile
Uses of RAM
» the user may wish to program in their own routines; these new instructions would be stored in the RAM chip
» the RAM chip will store the data/instructions received from the remote control unit
What are the 2 types of RAM and full forms
DRAM - dynamic RAM
SRAM - static RAM
What is DRAM made out of
Millions of transistors and capacitors
What is a capacitor in DRAM
Holds the bits of information (0 or 1)
What is a transistor in DRAM
Acts like a switch which allows chip control circuitry to read the capacitor/change the capacitor’s value.
Which type of RAM needs to be constantly refreshed otherwise what happesn
DRAM
Otherwise capacitors would lose their values.
How does SRAM hold memory and what makes it different
Doesn’t need to be constantly refreshed
Uses flip flops to hold data.
What does “refresh” mean in DRAM
recharge every few seconds in order to maintain
charge
What does a flipflop mean in SRAM
electronic circuit with only two stable conditions
Where is SRAM preferred and why
CPU’s memory cache, since it is faster.
Diff between DRAM and SRAM
DRAM:
Uses capacitors and trasnsitors to store data
Needs to be constantly refreshed
Consumes less power
Higher memory capacity.
Cheaper to manufacture
SRAM:
uses flip flops to hold each bit of memory
doesn’t need to be constantly refreshed
has a faster data access time than DRAM