1.1 structure and function of the CPU Flashcards Preview

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what is the ALU and what is its job?

the arithmetic logic unit, this carries out calculations and logical decisions.


what is the control unit and what is its job?

The control unit sends out signals to co-ordinate the processor. Controls how the data moves around parts of the CPU and how it moves between CPU and memory.


what are buses?

buses are a pathway for electrical signals to travel on.


what is a register?

a register is a memory location inside the processor that can hold one instruction.


what kind of registers are there?

-program counter
-memory data register
-memory address register
-current instruction register.


what is a program counter?

a program counter is a register that keeps track of the line of code being executed. It gets incremented to point to the next instruction, with each cycle of the FDE cycle, allowing the program to be ran line by line.


what is an accumulator?

an accumulator is a register that
stores the results of the calculations made by the ALU.


what is a MDR?

MDR is a memory data register and it stores the data that has been fetched from or stored in memory.


what is a MAR?

MAR is a memory address register and it stores the address of the data or instructions that are to be fetched or sent.


what is a CIR?

CIR is a current instruction register and it stores the most recently fetched instruction waiting to be decoded and executed.


what is machine code?

Machine code is binary instruction and is split into OPCODE and data it is very effective as it means the computer has to do less work to carry out the instruction but not user friendly.


what is assembly code?

Assembly code is one above machine code and allows the programmer to read/write code easier. The mnemonic for the op code is three letters.


what are high level languages?

High level languages like python is easiest for coding as it is easy to understand and read.


what is the FDE cycle/

FDE- fetch, decode, execute.


what is a clock cycle?

A single clock cycle is a complete FDE cycle.


what is clock speed measured in?

Clock speed is measured in hertz.


what is the advantage of having a faster clock speed?

The greater clock speed the more calculations can be carried out per second.


what is cache?

Cache memory is a special type of fast memory used for instructions and data likely to be needed by the processor.


what are the three levels of cache memory?

Three levels of cache memory are L1, L2 and L3.

L1 being the smallest and L3 being the biggest but furthest away from processor.

L3 is a shared cache between multiple cores.


what are the limitations of cache?

-it is very expensive.
-Must be physically small to fit onto the chip.
-Performance decreases as memory size increases.


why do processors usually have more than one core?

it becomes increasingly harder to improve clock speed so manufacturers increase the number of cores on a chip, more cores means the more data processed at the same time.


what is the disadvantage of multi core processors?

having more than one core, for example quad core, this does not mean the data is processed four times as fast as not all processes can be split down into multiple cores.


what is the John Von Neuman architecture?

In the john von Neumann architecture the programs and data is held in the memory; the processor and memory are separate and the data moves between the two.


what is the Von Neuman bottleneck?

The bottle neck is caused by the processor being so fast that it processes data faster than the memory can transfer it so the CPU is left idle longer the faster it is.


what is the Harvard architecture and how does it get rid of the bottle neck?

The Harvard architecture has two separate buses to the data and memory, this gets rid of the bottle neck as having two separate buses to instructions and the data memory gets rid of the delay of having the CPU idle waiting for the data.


what is a microprocessor?

A dedicated processor for carrying a specific, narrow or constrained task.


what is a SoC?

A SoC (system on chip) is a integrated circuit that has all components of a computer or other electronic system on a single chip.


what is pipelining?

loading the next instruction while the last one is being processed. it only works if the next instruction can be predicted.