Memory

Question 1

What are the factors that govern the type of memory used?

Answer 1

Speed
Cost
Capacity

Question 2

What is the aim of a Memory Hierarchy?

Answer 2

Obtain the highest possible access speed while keeping the costs low.

Question 3

What are the Categories of memory?

Answer 3

Primary Storage

Secondary Storage

Question 4

What is Primary Storage?

Answer 4

Stores small amounts of data and information that will be used immediately by the CPU.

Question 5

What are the three types of information Primary storage keeps?

Answer 5

Data (processed by CPU)
Instructions (how data will be processed)
OS programs (manages aspects of a computer's operation)

Question 6

What are the main types of Primary Storage?

Answer 6

Registers
RAM
Cache
ROM

Question 7

What is Register storage?

Answer 7

Has the least capacity, storing extremely limited instructions and data before and after processing.

Question 8

What are the facts of Register storage?

Answer 8

• 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

Question 9

What does RAM store?

Answer 9

RAM stores a software program and small amounts of data when brought from secondary storage.

Question 10

What are the types of RAM and explain them.

Answer 10

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.

Question 11

What is Cache?

Answer 11

An extremely fast memory built in a CPU or located in a separate chip near the CPU.

Question 12

What is Cache used for?

Answer 12

Cache is used for storing instructions/data that are repeatedly required to run a program to improve the system’s speed.

Question 13

What Cache is built in a CPU?

Answer 13

Level 1

Question 14

What Cache is stored in a separate chip?

Answer 14

Level 2

Question 15

How is Cache’s performance measured?

Answer 15

By Hit Ratio

Question 16

How do you measure a Hit Ratio?

Answer 16

(Total hit) ÷ (total hit + total miss)

Question 17

What does ROM store?

Answer 17

ROM stores programs and data permanently even when the computer is off.

Question 18

What software does ROM hold?

Answer 18

BIOS software that runs first when a computer is turning on.

Question 19

What program does ROM store and what does it do?

Answer 19

Bootstrap Loader.

It assists the start up of a computer.

Question 20

What are the different types of programmable ROM?

Answer 20

PROM (Programmable ROM)
EPROM (Erasable Programmable ROM)
EEPROM (Electronically EPROM)

Question 21

What is PROM?

Answer 21

Programmable ROM.

Where data can only be written once. When data is written onto PROM, it stays there permanently.

Question 22

What is EPROM?

Answer 22

Erasable Programmable ROM.

A PROM that can be erased and re-used. Contents can be erased by an ultraviolet light source.

Question 23

What is EEPROM?

Answer 23

Electronically Erasable Programmable ROM.

A ROM that can be erased and reprogrammed repeatedly through an application of higher voltage.

Question 24

What is Secondary Storage?

Answer 24

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.

Question 25

What is Subsequential Access?

Answer 25

Where a computer is required to run through data subsequentially to locate a piece.

Question 26

What is Direct Access?

Answer 26

Any item of data can be retrieved non-sequentially by locating with data’s address.

Question 27

What is a Magnetic Disk/Hard Disk?

Answer 27

A magnetised disk divided to tracks and sectors that provide addresses for various items of data.

Question 28

How is information recorded /stored in a Hard Disk?

Answer 28

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.