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1.1 Overview System Architecture (Embedded Systems (Computer systems built…
1.1 Overview System Architecture
Purpose of CPU
Hardware
Physical components of a CPU
Organisation
Motherboard is the main circuit board of the computer
The processor has direct access to everything on the board
Other devices can be connected to it via I/O controller
CPU
Main Memory
I/O controllers
Mouse
Disk Drive
Keyboard
Used as an interface between a hardware device external to the motherboard
Printer
VDU etc
Processor
Buses
Set of parallel wires connecting two or more independent components of a computer system
The system bus is split into three separate buses
Address bus
Bi-Directional
Can be read/written
Carries data/instructions from main memory to processor
Control Bus
Control signals are sent along control bus, eg memory read
This instructs that data will be travelling from memory to processor
Data bus
Carries addresses from processor to main memory
It works in only one direction
External Components (Peripherals)
Keyboard, mouse, printer, disks
Secondary Storage
Processor
Billions of electronic switches called transistors
Combined to make logic gates
Combined to create circuits
VERY FAST = 3 GHz (3000,000,000)
3 billion instructions every second
Main Memory RAM
Directly accessible by the processor
Everything is lost from RAM where the power is
Located on the motherbaord
Holds data and instructions that are currently in use by the processor
Main Memory ROM
Read only memory
Instructions are permanently etched onto a ROM chip
When power is turned off- instructions still remain on chip
The bootstrap loader is held on ROM
This is the set of instructions required to start up the operating system
Embedded Systems
Computer systems built into a machine
Provides a means of controlling the machine
Usually uses a single processor
Doesn't usually contain an OS
Limited functionality, but enough for the machine to fulfil it's purpose
Cheaper, reduced size, better reliability and usability compared to using a full computer system to do the same job
Examples:
Sat Navs
burglar alarms
washing Machines
Car Engine Management System