What is a computer system made up of?
Hardware (physical component) and Software (program that runs)
What must a computer system always have?
- CPU (processor)
- Input and Output device
- Primary Storage
- Secondary Storage.
What is an input device?
Takes real world data and converts it into a form to be stored on the computer
Examples of Output Devices
- Computer Screen
- Actuator
- Speaker
What is memory (primary storage)?
Used for holding instructions currently being executed and data that is being used
What did John Von Neumann develop?
Concept of stored program computer in 1940s
What did Von Neumann Architecture use the idea of?
- Holding both programs and data in memory
- Moved between memory unit and processor
What is the CPU?
- Central Processing Unit
- Executes programs
- Manages rest of hardware
What is cache memory?
- Very fast memory
- Close to CPU
- Temporarily holds data that is likely needed again by processor in course of running program
What is the Fetch-Decode-Execute Cycle?
- When run, processor must execute one instruction at a time
- By fetching it from main memory and decoding and executing.
What does the processor contain?
- Control Unit
- Arithmetic Logic Unit
- Registers
What is the Control Unit?
- Coordinates all activities in CPU
- Controls execution of instructions in correct sequence
- Decodes
- Regulates
- Sends and receives control signals.
What are the functions of the ALU?
- Arithmetic and Logic Unit
- Logic Operations : AND, OR, NOT
- Shift Operations : Shifting bits to left or right
- Arithmetic Operations : +, -, *, /
What is a register?
- Special, fast memory location within CPU
- Used in execution of instructions
What is the MAR?
- Memory Address Register
- Holds address of instruction fetched or stored
What is the MDR?
- Memory Data Register
- Holds data of program instruction temporarily when fetched or sent from/to memory
What is the PC?
- Program Counter
- Holds memory address of next instruction processed
What is the ACC?
- Accumulator
- Special memory location which results of ALU operations are stored
What affects CPU performance?
- Clock Speed
- Cache Size
- Number of Cores
How does clock speed affect CPU performance?
- Speed at which processor operates in hertz
- Faster clock means more instructions are fetched, decoded and executed per second
How does cache memory affect CPU performance?
- Frequently used data is stored temporarily
- Use of a small amount of cache improves speed by preventing constant reading and writing from main memory causing it to go slower
What is the pros of more cache memory?
More data and instructions can be held and made available quickly
What is the properties of Level 1 Cache?
- Extremely fast but small
What is the properties of Level 2 Cache?
Fairly fast and medium-sized
