Memory is used to store data/information and instructions. It is a data stroage unit or a data stroage device where data is to be processed and instructions required for processing are stored.
Problem
Memory gets incredibly expensive as it gets faster
Solution
1.
The hierarchy of memories:
a.
Fastest, smallest and most expensive memory per bit at the top
b.
Slowest, largest, cheapest memory at the bottom
Primary Memory
Secondary Memory
•
Fixed Storage
◦
Hard Disk Drives (HDD)
◦
Solid-State Disk (SSD)
◦
Internal Flash Memory
◦
etc.
•
Removable Storage
◦
Optical Disks
▪
DVDs
▪
CDs
▪
Blu-ray Discs
◦
Memory Cards
◦
etc.
Cache Memory
Locality of Reference
Temporal Locality
•
Programs tend to reference the same memory location at a future point in time
◦
Loops
◦
Iteration
◦
etc.
Spatial Locality
•
Programs tend to reference memory locations that are near other recently-referenced memory loc
◦
Contiguous Data Structure
◦
Array
◦
etc.
Sequential Locality
•
Programs tend to be accessed sequentially
