1.1.1 Architecture of the CPU Flashcards
What is a computer?
A computer is an electronic device which takes input, processes data, and delivers output
What is a computer program?
To process, computers follow a set of instructions known as a computer program
How does a computer carry out its function?
A computer carries out its function by fetching the instructions, decoding them and then executing them in a repetitive cycle
What happens during the fetch stage?
In the fetch stage, it fetches the next instruction from the main memory (RAM) and brings it back to the CPU
What happens during the decode stage?
In the decoding stage, the CPU inspects the instructions and works out what it is that needs doing
What happens during the execute stage?
In the execute stage, it carries out the instructions
How many cycles per second does a 1GHz processor do?
1GHz processor = 1 billion cycles per second
What can the ALU do?
The arithmetic logic unit can carry out arithmetic calculations and making logical decisions
What can the control unit do?
The control unit sends signals to control how data moves around the CPU
What is the cache?
The cache is a small amount of very fast memory
What is a register?
The registers are super-fast pieces of onboard memory inside the CPU each with a specific purpose
What are the 4 registers?
The 4 registers are the accumulator, the memory register, program counter and memory data register
What is a stored-program?
A Stored-program computer is one that has changeable programs
What was the first design for modern computers called?
In 1945, the mathematician and physicist, John Von Neumann described the first design for modern computers that had stored programs so the became known as the Von Neumann architecture
What are the key characteristics of the Von Neumann architecture?
*The key characteristics of the architecture are:
CPU
Single control Unit (CU)
Arithmetic Log Unit (ALU)
Onboard cache
Internal clock (it a pulse to synchronize components)
What does the PC do?
The PC (program counter) holds the memory address of the next instruction to be executed
What does the memory address register do?
The memory address register holds the address of where data is to be fetched from or stored into
What does the memory data register do?
The memory data register holds any data which has been fetched from memory or is about to be written to memory
What does the accumulator do?
The accumulator holds the results of calculations which has been performed by the arithmetic logic unit
How is the address used?
The address is used by the memory address register in order to fetch the instructions needed from the main memory and bring it back into the memory data register. The address in the program counter is added to point to the next instruction
What are the 3 factors that affect the CPU’s overall performance?
A CPU’s overall performance can be affected by many different factors. The three main ones are cache size, number of cores and clock speed
What is clock speed?
It’s the number of cycles per second. A Modern processors operate at billions of cycles per second, Gigahertz (GHz)
What is cache size?
Temporary storage of data and instructions being read to and written from the RAM. Stores copies of recent data and instructions. Much quicker getting instructions and data from memory if we don’t need to as it costs time
What is a core?
A complete copy of a CPU
What is an embedded system?
Embedded System is a computer system with a dedicated function within a larger mechanical system
