System Architecture Flashcards
What is the CPU?
The CPU (Central Processing Unit) is often thought of as the ‘brains’ of a computer. The purpose of the CPU is to fetch, decode and execute instructions.
It has two main functions:
- to process data and instructions
- to control the rest of the computer system
What is the fetch-execute cycle?
The CPU fetches the next instruction from RAM, it works out what to do with the instruction then carries out (executes) the instruction.
What is the Control Unit?
The Control Unit controls the flow of data inside the CPU (to registers) and outside the CPU to RAM and input/output devices. (manages. the instructions)
What is the Arithmetic Logic Unit?
The ALU performs all the arithmetic and logic calculations.
It completes simple addition and subtraction as well as comparisons
What are Registers?
The section of high speed memory within the CPU that stores data to be processed.
What is Cache?
The Cache is small, fast memory in the CPU. It is slower than the registers but faster than RAM. It stores frequently used data that the CPU can access quickly.
What are buses?
A channel of communication used to transport data and instructions in the CPU.
What are clocks?
A component of the CPU that sends out regular pulses. Its job is to synchronise the computer’s hardware components.
What is Von Neumann Architecture?
Von Neumann is based on the idea of a ‘stored program concept’. Both instructions and data are stored in the same memory in binary form.
What is the MAR (Memory Address Register)?
The MAR holds the address of where data is to be fetched or stored.
What is the MDR (Memory Data Register)?
The MDR holds the data fetched from or to be written to memory (RAM).
What is the PC (Program Counter)?
The PC holds the address of the next instruction in memory.
What is the Accumulator?
The Accumulator holds the intermediate results of calculations.
What are the three factors that affect the CPU’s performance?
Clock Speed
Cache Size
Number of Cores
How does Clock Speed affect the CPU performance?
This is the number of instructions a single processor core can carry out per second
How does Cache Size affect the CPU performance?
A larger CPU Cache gives the CPU faster access to frequently used instructions without having to fetch these instructions from RAM. This improves performance.
How does Number of Cores affect the CPU performance?
Each core in a CPU can process data independently. The more cores a CPU has the more instructions it can carry out at once.
What are Embedded Systems?
Embedded systems are computers built into other devices like dishwashers and microwaves. They have a special purpose and usually have a limited number of tasks they can perform. They are dedicated systems so are easier to design and produce
What advantages do Embedded Systems have over general purpose computers?
- Their limited number of functions means they are cheaper to design and build.
- They tend to require less power. Some devices run from batteries.
- They do not need much processing power. They can be built using cheaper, less powerful
processors.
What are examples of Embedded Systems?
- central heating systems
- fitness trackers
- GPS systems
- domestic appliances (dishwasher, microwave, TV, phone)
