1.1 Systems Architecture Flashcards
Hardware
Physical components that make up a computer
Software
Programs or applications that a computer runs
What do computers do?
Input
Process (done by CPU)
Stores
Outputs data
CPU full form
Central Processing Unit
CPU
The brain of a computer system
Processes data + instructions to make the system work
-> its processing power depends on other components
Main components of the CPU
CU
ALU
Cache
CU
Control Unit
Fetches, decodes and executes program instructions (by following the fetch-execute cycle)
Controls the flow of data in the CPU
ALU
Arithmetic Logic Unit
Performs all calculations: addition, subtraction, multiplication, division
Performs logic operations: AND, OR, NOT, binary shifts
How does the ALU do multiplication and division?
Repeated addition and subtraction
What does the ALU contain?
The accumulator
Cache
Data storage in the CU
Stores regularly used data so that the CPU can access it quickly when needed for operations
How does the CPU check for data?
It checks the Cache first, then the RAM
Disadvantage of Cache
Low capacity and expensive
Different levels of cache
L1 - quickest, lowest capacity
L2 - slower, higher capacity
L3 - slower, higher capacity
L4 - slower, higher capacity
The levels increase in size, and decrease in speed
Von Neumann Architecture
Describes a system where the CPU runs programs stored in memory
What is a program?
Consists of data + instructions
What does the CU contain?
Program Counter
What does the ALU contain?
Accumulator
What are the registers
MAR
MDR
Program Counter
Holds the memory address of the instruction for each cycle
MAR full form
Memory Address Register
MDR full form
Memory Data Register
MAR
Holds any memory address of an instruction or data, about to be used by the CPU
MDR
Holds the actual instructions or data
Memory
Holds program instructions or program data
Accumulator
Stores intermediate results of calculations in the ALU
Fetch - Execute Cycle
The process that the CPU uses to retrieve and execute instructions
FETCH in Fetch - Execute Cycle
- Copy memory address from program counter to MAR
- Copy instruction stored in MAR address to the MDR
- Increment program counter, ready for next cycle
DECODE in Fetch - Execute Cycle
- Instruction in MDR is decoded by the CU
EXECUTE in Fetch - Execute Cycle
- The instruction is performed
Factors that affect CPU performance
Clock Speed
Cache Size
Number of Cores
RAM Size
GPU
Clock Speed
The number of instructions that a single process can carry out per second (Hz)
Number of Cores
Each core works independently from eachother
GPU full form
Graphics Processing Unit
GPU
Specialised circuits for handling graphics + image processing
How Clock Speed affects CPU performance
Higher clock speed = more instructions carried out per second
How the Number of Cores affects CPU performance
More cores = more instructions carried out at once
How RAM Size affects CPU performance
More RAM = more applications can smoothly run
How GPU affects CPU performance
GPU = improved performance of graphic intensive applications (e.g. P.C. gaming)
Advantages of Embedded Systems
Easy to deign
Cheap
More efficient at doing the designated task compared to a general purpose computer
Embedded Systems
Computers inside a larger system/other device
What are Embedded Systems dedicated to?
A single task
Example of an Embedded System
Washing Machine
Microwave Oven
