Memory Flashcards
Learn each type of Memory and purpose
What are the factors that govern the type of memory used?
Speed
Cost
Capacity
What is the aim of a Memory Hierarchy?
Obtain the highest possible access speed while keeping the costs low.
What are the Categories of memory?
Primary Storage
Secondary Storage
What is Primary Storage?
Stores small amounts of data and information that will be used immediately by the CPU.
What are the three types of information Primary storage keeps?
Data (processed by CPU) Instructions (how data will be processed) OS programs (manages aspects of a computer's operation)
What are the main types of Primary Storage?
Registers
RAM
Cache
ROM
What is Register storage?
Has the least capacity, storing extremely limited instructions and data before and after processing.
What are the facts of Register storage?
- small set of storage locations used for a specific purpose
- manipulated by the Control Unit
- wired within the CPU for a specific function
- measured in bits or bytes
- stores instructions, data and address
What does RAM store?
RAM stores a software program and small amounts of data when brought from secondary storage.
What are the types of RAM and explain them.
SRAM (static) - fastest type of RAM but expensive. It is used within Registers and Cache.
DRM (dynamic) - cheaper type of RAM. It requires more power and generates more heat.
What is Cache?
An extremely fast memory built in a CPU or located in a separate chip near the CPU.
What is Cache used for?
Cache is used for storing instructions/data that are repeatedly required to run a program to improve the system’s speed.
What Cache is built in a CPU?
Level 1
What Cache is stored in a separate chip?
Level 2
How is Cache’s performance measured?
By Hit Ratio
How do you measure a Hit Ratio?
(Total hit) ÷ (total hit + total miss)
What does ROM store?
ROM stores programs and data permanently even when the computer is off.
What software does ROM hold?
BIOS software that runs first when a computer is turning on.
What program does ROM store and what does it do?
Bootstrap Loader.
It assists the start up of a computer.
What are the different types of programmable ROM?
PROM (Programmable ROM)
EPROM (Erasable Programmable ROM)
EEPROM (Electronically EPROM)
What is PROM?
Programmable ROM.
Where data can only be written once. When data is written onto PROM, it stays there permanently.
What is EPROM?
Erasable Programmable ROM.
A PROM that can be erased and re-used. Contents can be erased by an ultraviolet light source.
What is EEPROM?
Electronically Erasable Programmable ROM.
A ROM that can be erased and reprogrammed repeatedly through an application of higher voltage.
What is Secondary Storage?
Stores larger amounts of data for extended time. It is non-volatile. It takes more time to retrieve data due to electromechanical nature. It is also cheaper than Primary storage.
What is Subsequential Access?
Where a computer is required to run through data subsequentially to locate a piece.
What is Direct Access?
Any item of data can be retrieved non-sequentially by locating with data’s address.
What is a Magnetic Disk/Hard Disk?
A magnetised disk divided to tracks and sectors that provide addresses for various items of data.
How is information recorded /stored in a Hard Disk?
Each disk has concentric circles called “Tracks”. Information is recorded on tracks as Tony magnetic spots which represents bit 1 and 0. Information stored in a disk can be read multiple times without causing affect on the data.
