What does CPU stand for?
Central Processing Unit
How does the computer carry out instructions given to it?
Fetch —> Decode —> Execute
(Repeats billions of times)
What happens during ‘fetch’?
The next instruction isbfetched from RAM and brings it back into the CPU
What happens during ‘decode’?
The instruction is decoded. The CPU breaks down the instruction and works out what it needs to do
What happens during ‘execute’?
The instruction is carried out
What is a ‘clock speed’?
It’s what measures how fast a computers CPU can execute instructions
What is clock speed measured in?
Gigahertz (GHz)
How many instructions can 1 GHz execute?
1 GHz = 1 billion cycles per second
Computer A has a clock speed of 4 GHz and computer B has a clock speed of 2 GHz, which computer can execute the most instructions per second?
Computer A
What is the Arithmetic logic unit (ALU)?
Its responsible for carrying out arithmetic calculations and making logical decisions
What is the control unit (CU)?
It’s sends signals to control how data moves around the CPU
What is Cache?
Its a small amount of very fast memory, which is typically located very close to the CPU or inside it.
Provides fast access to frequently used instructions and data
What are registers?
Tiny, super fast pieces of onboard memory inside the CPU. Each has a specific purpose.
Who designed computers with stored programs and when?
In 1945, the mathematician and physicist Jon Von Neumann, described the first design for modern computers that had stored programs
What were computers designed with stored programs known as?
Von Neumann architecture
List 4 types of registers
Accumulator
Memory Address Register (MAR)
Program Counter (PC)
Memory Data Register (Data)
What does the Program Counter do?
Holds the address of the next instruction to be executed by memory
What does the Memory Address Register (MAR) do?
Holds the address of where data is to be fetched or stored
What does the Memory Data Register do?
Holds the data fetched from, or to be written to memory
What does the Accumulator do?
Holds the results of calculations
What is RAM?
Main memory/ Random Access Memory
What is ROM?
Read only memory
What is primary storage?
The components of a computer that holds data, programs and instructions that are currently in use.
What are TWO examples of primary storage?
Read only memory (ROM)
Random access memory (RAM)
