THE VISIBLE PC Lecture 2: A look at the brains of the computer, the motherboard, and its associated components. Networks and Communication Department 1

Networks and Communication Department

THE VISIBLE PC

Lecture 2: A look at the brains of the computer, the motherboard, and its associated components.

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Outline

1. Inside a PC2. The Motherboard3. Motherboard Power Connector (P1) 4. RAM5. ROM6. CMOS Memory7. The CPU8. Expansion Slots9. Chipsets10. External Connections

types of memory

the 'brains'

the processor


The complete PC

All of the processing and storage takes place in the system unit

All other parts of the PC – the printer, the keyboard, the monitor – connect to the system unit and are known as peripherals.

The system unit’s case protects the internal components from the environment


Typical PC case

Power supplyCD-ROM drive

Floppy disk drive

Hard disk drive

Wires andribbon cables

Sound/networkcards

Motherboard


Inside the System Unit


Motherboard

Is a thin, flat piece of circuit board, usually green or gold, and often slightly larger than a typical piece of notebook paper.

It holds: The processor chip Memory chips Special sockets Multipurpose expansion slots onboard connector (I/O)

Some chips are soldered onto the motherboard(permanent), and some are removable (so they can be upgraded).


Motherboard (Cont.)

Expansion slots

RAM

CPU

Onboard connector

Sockets

Video card



Motherboard Power Connector (P1)

The motherboard would do nothing without power going through it.

(P1) Power Connector connects between the power outlet on your wall and the computer components.


Motherboard Power Connector (P1)

(P1) Power Connector powers the objects

on the motherboard like CPU and memory

It does not power the hard-drive, CD-ROM

or floppy drive so they need their own

power connectors


RAM

Random Access Memory (RAM).

RAM is used to hold programs while they are

being executed, and data while it is being

processed.

Measured in units called bytes

RAM is volatile, meaning that information written

to RAM will disappear when the computer is

turned off.


RAM (Cont.)

RAM contents can be accessed in any (i.e. random) order.

Each piece of RAM is called stick on common type of stick called a dual

inline memory module (DIMM) You can install extra RAM.(same type)


RAM (Cont.)

Each RAM locationhas an address and holds one byte of data (eight bits).


RAM (Cont.)

WHAT HAPPENS WHEN THE COMPUTER RUN OUT OF

RAM ?


RAM (Cont.)

Virtual memory uses part of the hard

disk to simulate more memory (RAM)

than actually exists.

It allows a computer to run more

programs at the same time.

Virtual memory is slower than

RAM.


ROM

Read-Only Memory can

be read but not changed.

It is non-volatile storage: it remembers

its contents even when the power is

turned off.

ROM chips are used to store the

instructions a computer needs during

start-up, called firmware.


ROM (Cont.)

Every motherboard comes with a small

code that enables the CPU to connect

with other devices

This program is called Basic Input/Output

System (BIOS)

The BIOS is stored inside a Flash ROM

(system ROM)


CMOS Memory

Separate memory chip called the complementary metal oxide semiconductor (CMOS)

Stores the information that describes specific device parameters

This data read by BIOS to complete the programs needed to talk to changeable hardware

It also acts as clock to keep the current date and time

the battery


Date and Time Battery

This battery is not the source of your

computer power

It enables your computer to retain the

accurate time and date


CPU

The central processing unit (CPU), also called the microprocessor or processor

performs all the calculations that take place inside a PC.

CPUs come in a variety of shapes and sizes.


CPU (Cont.)

a cooling fan and heat sink assembly to avoid overheating

A heat sink is a big slab of copper or aluminum that helps draw heat away from the processor.

The fan then blows the heat out into the case.


CPU (Cont.)

The two most common makers of CPUs

used in PCs are AMD and Intel.

Some of the more common models made

over the last few years have names such

as Celeron, Athlon, Sempron, Pentium III,

Pentium 4 , I3, I5 and I7.

CPUs come in different packages.


Expansion Slots

Expansion slots allows you to customize your computer by adding components through them.

Common expansion cards: graphics card (for connecting to a monitor) network card (for transmitting data over a

network) sound card (for connecting to a microphone and

speakers)


Expansion Slots (Cont.)

Most PCs offer 4-8 expansion slots.

There are several different types of expansion slot:

ISA: (Industry Standard Architecture) older

technology, for modems and slow devices

PCI: (Peripheral Component Interconnect) for

graphics, sound, video, modem or network cards

AGP: (Accelerated Graphics Port) for graphics cards


Expansion Slots (Cont.)

Most expansion cardscontain a port.

A connector cable plugsinto the port, and leads to a peripheral.

Expansion slot containing an expansion card.


Chipset

There are 2 chipset chips to facilitate

communication between the CPU and

other devices :

Northbridge and Southbridge



Chipset (Cont.)

The Northbridge helps the CPU connect

with RAM, It deals with high speed

interfaces

The Southbridge connects the CPU with

the expansion devices and storage drives

like Hard-drive and floppy-disk-drive, It

works mainly with lower speed devices


External Connections


External connections

A Plug is a part with some type of

projection that goes into a port

A port is a part that has some type of

matching hole or slot that accepts the

plug

The jack is used as an alternative to port

The connector describes either a port or

a plug


External connections (Cont.)1. Mini-DIN Connectors: The original DIN connector was replaced

by mini-DIN Older style keyboards and mice plug into

mini-DIN ports


External connections (Cont.)2. USB Connectors Universal serial bus (USB) The most common general-purpose

connection for PCs. Many different devices, such as mice,

keyboards, scanners, cameras, and printers. USB connections come in three different

sizes: A (very common), B, and mini-B (less

common).


USB Connectors (Cont.)

The USB A connector’s distinctive rectangular shape makes it easily recognizable (as shown in Figure)


USB B connectors are for the other end of the USB cable where it attaches to the USB device (as shown in Figure).

The smaller mini-B-style connector (as shown in figure)

For small devices such as camera

USB B connectors Mini-USB Connectors




USB has a number of features that make it particularly popular on PCs.

1. USB devices are hot-swappable, which

means you can insert or remove them

without restarting your PC.

2. many USB devices get their electrical

power through the USB connection


External connections (Cont.)3. FireWire Connectors Moves data at incredibly high speeds,

making it the perfect connection for highly specialized

applications, such as streaming video from a digital video camera onto a hard drive


FireWire Connectors (Cont.)

FireWire consists of a special 6-wire connector, as shown in Figure.

There’s also a smaller, 4-pin version, usually seen on peripherals.

Like USB, FireWire devices are hot-swappable.


External connections (Cont.)4. DB Connectors Over the years, DB connectors have

been used for almost any type of peripheral you can think of, with the exception of keyboards.

They have a slight D shape, which allows only one proper way to insert a plug into the socket.


DB Connectors (Cont.)

DB connectors in the PC world can have from 9 to 37 pins or sockets, although you rarely see a DB connector with more than 25 pins or sockets.

DB-type connectors are some of the oldest and most common connectors used in the back of PCs.


External connections (Cont.)

5. RJ Connectors The little plastic plug used to connect your

telephone cord to the jack is a classic example of an RJ plug.

Modern PCs use only two types of RJ jacks: the RJ-11 and the RJ-45.

The phone jack is an RJ-11. It is used almost exclusively for modems.

The slightly wider RJ-45 jack is used for your network connection.

Figure shows an RJ-11 jack (bottom) and an RJ-45 jack (top).


External connections (Cont.)6. Audio Connectors Speakers and microphones connect to

audio jacks on the system unit. The most common type of sound

connector in popular use is the mini-audio connector.


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Any Questions ?


References

Mike Meyers, “CompTIA A+ Certification, all-in-one”, sixth edition, chapter 2, p. 30 – 53

Mike Meyers, “Introduction to PC Hardware and Troubleshooting”, first edition, chapter 4 , p. 84 – 93.

Documents

THE VISIBLE PC Lecture 2: A look at the brains of the computer, the motherboard, and its associated components. Networks and Communication Department 1