CP1610:Introduction to Computer Components
The Motherboard
What is the Motherboard?
The largest circuit board in a computer. The means by which all devices are
connected to each other, and the CPU. Also called the system board.
Parts on a Motherboard
What is the CPU
Central Processing Unit. Also called the processor or the
microprocessor. The most important chip in the computer. The brain, or command centre.
Parts of the CPU
Input/output (I/O) unit
Arithmetic logic unit(s) (ALU)
Control unit
How the CPU Works
Please wait until the road is clear, and I will
open the gate!
The I/O Unit is like the security guard at the front gate.
You need to go to Building 10!
The Control Unit (CU) is like a security guard directing students to the correct building.
Parking
Parking
(Internal Cache)
(Registers)10 9
ALU ALU
CISC vs. RISC Processors
CISCComplex Instruction Set Code
RISCReduced Instruction Set Code
CISCRISC
Other Parts on the Motherboard
System Bus CMOS BIOS The Chipset System Clock Expansion Slots Floppy and Disk Drive Connections Memory
System Bus
Metal lines (traces) connecting parts on the motherboard.
Allow data to travel between devices and the CPU.
Like a system of roads throughout a city. Can be expanded to other parts (like
highways connecting towns and cities).
CMOS
Chip that saves your system settings:Date and timeHardware configurationBoot device order
Has a battery so that it can save your settings even when the computer is off
CMOS stands for Complex Metal Oxide Semiconductor
BIOS
Basic Input/Output System Stores basic instructions on how the computer
can talk to: Keyboard Mouse Monitor Memory
Allows a computer to operate basic functions without any other software installed
Is the same for ALL computers.
The Chipset
The chipset controls most parts of the computer.
It handles ‘routine’ work, so the CPU can handle more important processing.
Some of the chips in the chipset include: Interrupt ControllerKeyboard ControllerDMA Controller
The Interrupt Controller
What is an Interrupt?Lots of devices want to get the CPU’s
attention;An interrupt is a signal that tells the CPU
which device is calling, or sending data;The Interrupt Controller is a chip that controls
the flow of data on the system bus, and lets the CPU know which device needs it;
Who is trying to call me? This better
be important!
Don’t worry… I can direct
traffic for you!
The CPU(Everyone wants his attention!)
The Interrupt Controller is like a police offer directing traffic at a busy roundabout.
Some devices get priority over others
How the Interrupt Controller Works
CPU1
2
0
3
4
5
7
6
8
9
11
10
13
12
14
15
System Clock
Keyboard
Floppy
PS/2 Mouse
Inte
rrup
t Co
ntro
ller
Inte
rrup
t Co
ntro
ller
Common Interrupt Requests (IRQ’s)
IRQ USUAL FUNCTION/DEVICE
0 System Timer
1 Keyboard
2 2nd IRQ controller
3 COM2:
4 COM1:
5 Free (used by LPT2: or sound card)
6 Floppy disk
7 LPT1:
8 Real Time Clock (RTC)
9 Free (may be labeled/appear as IRQ 2)
10 Free (often used by sound cards)
11 Free
12 PS/2 mouse
13 Math coprocessor on CPU (used)
14 Primary IDE
15 Secondary IDE
Keyboard Controller
The Keyboard Controller provides the following functions:Keyboard Control and Interpretation.PS/2 Mouse Support.Access to the High Memory Area.
The Keyboard Controller is often not needed in newer computers.
The DMA Controller
Direct Memory Access Sometimes devices may want to ‘talk’ to
each other without ‘going through’ the CPU.
DMA Controller controls access to the system bus, and RAM, and bypasses the CPU.
I’m busy with official business… don’t bother
me!
Thanks, officer. I guess I don’t need to bother with
this car!
The CPU(Not everyone needs his attention!)
The Interrupt Controller
Some devices don’t need to talk to the CPU
I’m only going to McDonald’s! Do I really need to go see the CPU
first?
Don’t worry, Sarge! I’ll direct this car through the
roundabout!
The DMA Controller is like a second traffic officer who handles traffic not going to the CPU
This better be important if you want to keep going down
Madinat Khalifa!
Can I go now?
Beep! Beep!
The System Clock
Crystal that emits a pulse/signal.
Acts like a drummer in a rock band.
Pulses provide timing for the CPU and other devices.
Clock Speeds
Measured in HertzCycles per second
Speed of the Motherboard:Megahertz (MHz)
Speed of the CPU:Gigahertz (GHz)
Expansion Slots
Allow you to ‘expand’ the capabilities of your computer.
Connect new circuit boards to your motherboard.
Connect the data buses (roads) on the expansion cards to the system bus (roads) on the motherboard.
Common Expansion Cards
Sound Cards Modems Network Cards Video Cards Specialty Cards
Types of Expansion Slots
ISA Industry Standard Architecture Older, ‘legacy’ cards
PCI Peripheral Component Interconnect Newer, faster expansion cards
AGP Accelerated Graphics Port
Floppy and Disk Drive Connections
Special slots for ‘ribbon’ (data) cables. Allow you to connect:
Floppy disk drives;Hard disk drives;CD/DVD drives;Zip disk drives;Etc…
Floppy Drives
There is usually only one floppy disk drive connection.
A floppy controller chip on the motherboard controls talking to, and fuctions of the floppy drive.
EIDE Connections
Used to connect:Hard disk drives;CD/DVD drives;
Two connectors on the motherboard.Each connector can connect two devices;Up to four EIDI devices can be connected;
Memory Devices
Hold data and instructions. Types of Memory:
System Memory;RAM;ROM;
System Memory
1 Megabyte (1 MB) Built into motherboard. Maximum memory that could be handled by:
Older PC’s; New PC’s before system drivers and OS are booted;
Hold data and instructions for: System drivers; Programs used by the user;
Available to the user for any software
Reserved for device drivers and system functions
Anything above 1 MB
RAM vs. ROM
RAM Random Access
Memory Stores data and
instructions Volatile
Examples: RAM chips CMOS
ROM Read Only Memory Stores basic system
settings Non-volatile
Example: BIOS
Types of Motherboards
Choice of motherboard affects:Capabilities and limitations of system;Type of computer case needed;
Common types of motherboards:ATATXBackplane
The AT Motherboard
Smaller Used for classic
Pentium CPU Uses SIMM RAM Uses P8 and P9
power connectors
The ATX Motherboard
Faster Easier to install More power
management features Uses DIMM RAM Has a PI power
connector
Backplane Motherboards
Actually built into the computer case. More difficult to make upgrades. Not as popular.