architecture of the CPU flashcards

what is a computer?

an electronic device that takes input, processes data and outputs a result. it may also communicate and store processed data.

CPU

Central Processing Unit

• purpose is to process and execute instructions

main components of the CPU and functions

• Arithmetic Logic Unit (ALU) - performs calculations

• Control Unit (CU)- decodes instructions and sends signals to control how data moves around the CPU.

what are registers?

tiny, super-fast pieces of onboard memory, inside the CPU, each with a specific purpose

registers in the CPU

• Memory Address Register (MAR)

• Memory Data Register (MDR)

• Program Counter (PC)

• Accumulator (ACC)

MAR

Memory Address Register

stores the memory address where data is to be stored or fetched

MDR

Memory Data Register

holds data fetched from or to be written to the main memory

PC

Program Counter

holds the address of the next instruction

ACC

Accumulator

holds the results of calculations

cache

memory that provides fast access to frequently used instructions and data without having to go back to the main memory (RAM)

why do we need cache?

• improves performance of computer - reduces number of times that the processor has to access main memory

• by storing frequently accessed data in cache, the processor can access data more quickly

what factors affect CPU performance?

• clock speed

• number of cores

• cache size

how does clock speed affect the CPU’s performance?

the faster the clock speed, the faster instructions are processed. (the faster the CPU will run)

how does cache size affect the CPU’s performance?

cache is faster than main memory (RAM).

the larger the cache size, the less time will be spent accessing the RAM and for the processor to wait for instructions to be fetched → CPU will work faster

how does the number of cores affect the CPU’s performance?

the more cores a CPU has, the greater the number of instructions it can process in a given space of time.

 von Neumann architecture

based on the stored-program concept, meaning both instruction data and program data are stored in the same memory in binary form

fetch-execute cycle

1. Data is fetched from main memory (RAM) into the CPU/registers to be decoded

2. CPU decodes instructions to be ready for processing

3. CPU performs/process instructions

embedded system

a computer system with a dedicated function within a larger mechanical system. examples:

• traffic lights

• hospital equipment

• factory equipment

typical properties of embedded systems

• Low power consumption

• Small size

• Rugged operating ranges

• Low cost per unit