Internal Hardware

• Main memory is memory that can be accessed directly by the processor. 
• There are two types of main memory: ROM and RAM
• A bus is a communication system that is used to transfer data between components.
• The components of a computer system are connected together using buses
• The Processor executes instructions
• The Main memory stores instructions that are frequently used, for example RAM.
• A Bus is a series of parallel wrires that connects the internal components of a computer.
• There are 3 types of buses, Address, Data and Control
• Address Bus transports memory addresses, it tells us where memory should go
• Control Bus carrys control signals
• Data Bus transports data and instructions
• I/O(Input/Output) Controllers control communication between processor and hardware
• There are two types of Processor set ups: Harvard Architecture and Von Nuemann
• Harvard Architecture is Better
• Harvard Architecture has 2 seperate main memory, one for instructions and one for data. Because of this it can give different characteristics to each memory.
• Von Nuemann has 1 main memory, holding both instructions and data. Because of this it performs worse because buses have to be shared.
• Harvard Architecture is used in embedded systems, but Von Nuemann is used in General purporse computers such as a phone
• the stored program concept: machine code instructions stored in main memory are fetched and executed serially(in order) by a processor that performs arithmetic and logical operations