Principles of computer science

Question 1

Von Neumann architecture

Answer 1

DIAGRAM:
__________Main Memory
________ (Read)!_____¡(Write)
Input –> Central Proecessing Unit –> Output

• A structure in which computer hardware is connected and organised.
• It consists of RAM and CPU interconnected by buses.
• The CPU reads and writes data & program instruction to and from main memory (RAM)

Question 2

Main memory

Answer 2

Known as Random Access Memory(RAM)
It stores the data & programs the CPU can access.
Volatile - Loses content when power is lost.

Faster and more expensive than secondary storage

Question 3

Programmable computer

Answer 3

A computer that is multi-purpose, can be programmed to carry out different tasks. They are able to store program instructions and data in memory.

Question 4

The CPU consists of…

Answer 4

• Control Unit (CU)
• Arithmetic logic unit (ALU)
• Registers
• Clock

Question 5

Control Unit (CU)

Answer 5

The control Unit decodes information received from main memory and coordinates the actions of the other parts of the CPU

Question 6

Arithmetic Logic unit (ALU)

Answer 6

Performs arithmetic and logic operations on data

Question 7

Registers

Answer 7

Provides fast and temporary storage for instructions

Question 8

Clock

Answer 8

Sends out electrical signals to synchronise the actions of the hardware components. Measured in hertz, 1 hertz = 1 “tick” per second

Question 9

Busses

Answer 9

Busses connect the CPU with the main memory. There are 3 types of busses:

• Adress bus
• Data bus
• Control bus

Question 10

Secondary Storage

Answer 10

Non-volatile
Allows the system to store data and programs permanently.
Types:
-SSD(Solid State Drives): USB drive
-HDD(Hard Disc Drive): Magnetic storage
-Optical Storage: DVD/CD

Cheaper and slower than main memory.

Question 11

Solid State Drive

Answer 11

Represents bits by little pools of trapped electrons on a microchip

Question 12

Binary System

Answer 12

Components inside computers have billions of transistors. Binary is used to represent the transistors inside the component. Transistors can be on or off (1 or 0).

Question 13

Fetch

Answer 13

CPU sends through the address bus the memory address of the next instruction
The CU within the CPU sends a read message to the memory through control bus
The content of the memory locations is sent to the CPU via the data bus

General: The next instruction to be executed is transferred from the RAM to the CPU

Question 14

Decode

Answer 14

The CU looks up the instruction in the CPUs instruction set

Question 15

Execute

Answer 15

CU coordinates the action of other components to carry out the operation and instructs the ALU if calculations needed to be done

Question 16

Why is binary used?

Answer 16

Components inside computers have billions of transistors. Binary is used to represent the transistors inside the component. Transistors can be on or off (1 or 0).

Question 17

Signed / unsigned integer

Answer 17

An unsigned integer has no positive or negative sign.
Signed: -8, +8
Unsigned: 8