What is the Principle of Locality?
The CPU usually keeps using the same small group of memory locations again and again.
What are the two forms of locality?
Temporal locality and Spatial locality.
Define Temporal Locality.
Recently accessed memory locations are likely to be accessed again soon.
Define Spatial Locality.
Memory locations near recently accessed addresses are likely to be accessed soon.
What are the key characteristics of computer memory systems?
Location, Capacity, Unit of Transfer, Access Method, Performance, Physical Type, and Organization.
What are the types of access methods?
Sequential, Random, Direct, and Associative.
What is Sequential Access?
Data is read or written in order (e.g., magnetic tape).
What is Random Access?
Any memory location can be accessed directly and instantly (e.g., RAM).
What is Direct Access?
Combines random and sequential; used in disks.
What is Associative Access?
Data is located by content rather than address (e.g., cache memory).
What are the performance parameters of memory?
Access time, Cycle time, and Transfer rate.
What is Virtual Memory?
A technique allowing a system to use part of secondary storage as an extension of main memory.
What are the design principles of memory hierarchy?
Locality, Inclusion, and Coherence.
What is Inclusion in memory hierarchy?
Each level holds a subset of data from the lower (larger) level.
What is Coherence?
Ensures copies of data across levels are consistent.
What is Average Memory Access Time (AMAT) formula?
AMAT = (L1 Hit Time) + (L1 Miss Rate) × (L2 Hit Time) + (L1 Miss Rate × L2 Miss Rate × Main Memory Time).
How does cost per bit change in the hierarchy?
It increases from bottom to top.
How does capacity change in the hierarchy?
It increases from top to bottom.
