Hardware Basics: Inside the Box

Miguel Rebollo

Introduction to Computer Science2009-2010

4626. Introd to Computer Science

Aims

• Know how information is stored and handled into a computer

• Describe the basic structure of a computer

• Functions and interactions of computer’s internal components

• Difference memory types and storage devices

4626. Introd to Computer Science

Outline

1. What computers do

2. A bit about bits

3. The computer core: CPU and memory

4. Buses, ports and peripherals

4626. Introd to Computer Science

What computers do

• Receive input data

• Process this information: perform arithmetic or logic (decision-making) operations

• Produce output: communicate information to the outside world

• Store information: move data to the memory

4626. Introd to Computer Science

Basic components

Input devices:keyboard

and mouse

Output devices:screen, printer, speakersCPU

Memory

Storage

4626. Introd to Computer Science

Von Newman archit.

CPU

memory

input/outputsystem

bus(*)i/o bus

(*) front side bus

4626. Introd to Computer Science

A bit about bits

• computer’s information is digital

• Bits can represent letters, numbers, instructions, codes, colours and so on

• 8 bits = 1 byte (256 different values)

4626. Introd to Computer Science

Bits as numbers

There are only

10 types of people in the world:

those who understand binary

and those who don’t

4626. Introd to Computer Science

Binary number system

• All numbers as combinations of two digits: 0 and 1 (base 2)

• conversion binary-decimal

• with n digits we have 2n possibilities

decimal binary0 0001 0012 0103 0114 1005 1016 1107 111

Play with the numbers

4626. Introd to Computer Science

Bits as characters

• Each character has its representation in bits

• ASCII (see table)

• the most widely spread

• fixed codification (1 character = 1 byte)

• Unicode (UTF)

• until 65,000 char., language independent

• variable codification (1 or 2 bytes)

4626. Introd to Computer Science

ASCII code

• ASCII code uses 8 bits

• 8 bits produce 28=256 possibilities

• It’s not enough, several codes added

• mutually incompatible

• changes in special letters (ñ, á, ç, ...)

4626. Introd to Computer Science

Bits, bytes and buzzwords

• Bit-related terminology

• Other units: Zettabyte, Yottabyte...

• See Data Powers of Ten

1 Byte =1 kilobyte (kB) = 1024 Bytes1 megabyte (mB) = 1024 kB1 gigabyte (gB) = 1024 mB1 terabyte (tB) = 1024 gB1 petabyte (pB) = 1024 tB1 exabyte (eB) = 1024 pB

4626. Introd to Computer Science

The computer’s core: CPU

• It’s the main component of the computer

• Executes program’s instructions

• Instructions are stored in memory

• Input data and results are stored in memory too

4626. Introd to Computer Science

Evolution of Intel proc.

Intel processor history

4626. Introd to Computer Science

CPU equivalenceIntel AMD

Obsolete Pentium 4 Athlon 64Low-end Celeron Sempron

DesktopCore 2 Duo, i3, i5 Athlon 64 x2

DesktopCore 2 Quad, i5, i7 Phenom

Laptop Centrino, i3, i5 TurionNetbook Atom -----

Servers/Workstation

Xeon OpteronServers/Workstation Itanium -----

4626. Introd to Computer Science

CPU performance

• The computer’s overall performance is determined by (among others)

• the internal clock (gHz): cycles per second

• the internal architecture

• Two technologies: CISC and RISC

• Multiple core and Hyperthreading tech.

4626. Introd to Computer Science

CPU compatibility

• Each CPU has its own instruction set depending on the manufacturer (Intel, Alpha...)

• CPUs in the same family are designed to maintain backwards compatibility (new models interprets all instructions from earlier CPU)

4626. Introd to Computer Science

RAM memory

• it’s volatile

• divided in smaller elements (bytes) identified by its address and managed individually

Stores temporally program instructions and data

4626. Introd to Computer Science

ROM (read only memory)

information stored in chips

contains startup instructions

4626. Introd to Computer Science

Other memories

• CMOS (Complementary Metal Oxide Semiconductor): Special low-energy kind of RAM

• Flash memory: used in phones, PDA or cameras

4626. Introd to Computer Science

Buses, ports and peripherals

• Information travels between components on the motherboard through groups of wires called system buses (or just buses)

• They have 32 or 64 parallel wires

• Expansion slots, bays and ports: connect additional devices