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Computer Hardware
The Processing
Unit
The Computer System
InputDevices
OutputDevices
StorageDevices
CommunicationDevices
Processing Unit
The Processing Unit
• The main part of a microcomputer is called the System Unit
• Most of the processing hardware is on the motherboard
The Processing Unit
• The motherboard is the main circuit board in a computer
A circuit board is a sheet of fiberglass on which electronic components are solderedThese components are connected with traces of copper printed on the surface
The Motherboard
1 – The CPU
2 – The Chipset
3 – Main Memory
4 – The System Bus
5 – The System Clock
FiveMain
MotherboardComponents
The CPU
CPU
Control Unit ALU Registers
The Central Processing Unit has 3 parts
The Control Unit
The Control Unit• Regulates the flow of information• Monitors all operations performed by the
system• Runs Programs:
Fetches program instructions from memory Increments the Program CounterDecodes the instruction Executes the instructionWrites results to memory
The ALU
The Arithmetic and Logic Unit• Performs all calculations (+, - ,*, /)• Returns the result of simple logic
decisions ( is x > y true or false?)• Calculations can be accelerated by a
Floating Point Unit (FPU)
Registers
• Registers• A small amount of high-speed memory on
the CPU• Registers hold the current program
instruction and data • Very fast but also expensive
The Chipset
• A chipset is a group of ICs (Integrated Circuits or computer chips) that are designed to support the CPU.
• On most PC motherboards the chipset has two microprocessors often called the Northbridge and the Southbridge.
The Chipset
The Northbridge chip links the CPU to high-speed components like main memory and video controllers.
The Chipset
The Southbridge chip then links to lower-speed peripheral devices through connections like PCI or PCI-Express.
The Southbridge may also have built-in Ethernet (networking), USB or audio device support
The System Bus
In computers, a bus is a set of connections (wires) that is shared by multiple hardware components in order to communicate.
Bus
A general term for the bus on a motherboard that connects the CPU to all the other components. Also called a local bus.
SystemBus
The System Bus
The main bus between the CPU and main memory typically through the Northbridge.
Frontside
Bus
A common type of local bus that is used to connect the Southbridge chip to peripheral devices such as network expansion cards.
PCIBus
Main Memory-1
CPU
Registers
• Inside the CPU is a small amount of high-speed, expensive computer memory called registers.
• The registers are used for storing data currently being processed in the CPU
Main Memory-2
Main Memory
Ram
CPU
• Most data is stored in Main Memory.• There are two types of Main Memory: RAM &
ROM
Main Memory-3
Main Memory
Ram
Cache
L1
CPU
• Between Main Memory and the CPU is a buffer or temporary storage called cache (pronounced like cash)
• Cache memory stores data so that future requests for that data from the CPU can be served faster.
Main Memory-4
The System Clock
• On the motherboard is a component that generates a clock signal
• This is a timing signal that synchronizes all data transfer in a computer system.
• The CPU also executes instructions at a speed set by the clock signal
The System Clock
• Clock rates are measured in hertz (cycles per second)
• Household AC current alternates at 60 Hertz
German physicist Heinrich Hertzmade important scientific contributions
to the study of electromagnetism.
• 1 megahertz (MHz)= 1 million hertz
• 1 gigahertz (GHz)= 1 billion hertz
The Motherboard
CPU
RAMROM
(BIOS)
Southbridge
ExpansionSlots Northbridge
Ports
A Motherboard