1.2 Memory And Storage

Question 1

Define primary storage

Answer 1

Memory that the cpu can access

Question 2

Define secondary storage

Answer 2

Non volatile, permanent storage

Question 3

3 forms of primary storage

Answer 3

1) ROM (read only memory): holds the boot up sequence for the computer. Non volatile, will retain contents even if there is no power

2) RAM (random access memory): holds data and instructions for programs that are currently running. Volatile, temporary memory, contents are lost when power is turned off

3) CACHE: super fast RAM that is located near the cpu. Holds frequently used instructions

Question 4

3 types of secondary storage

Answer 4

1) Solid state: durable so suitable for portable devices. No moving parts. Fast read and write times. Physically small.

2) magnetic: a stack of magnetised metal desks. Data is stored magnetically in sectors. Moving parts sk vulnerable. High capacity and reliable

3) optical: cheap to manufacture. Limited capacity. Data is stored by making microscopic indentations in the surface of the disk. This changes the angle of a beam of light. One angle will mean a 1, the other 0

Question 5

What is virtual memory

Answer 5

When RAM becomes full, a section of secondary storage is used to act as temporary RAM. Instructions that are not currently in use can be moved to virtual memory to free up space in RAM. If instructions in virtual memory are needed, they must be moved back to RAM. If there is no space, other instructions can be swapped. Instructions can only be executed from RAM, not directly from virtual memory