Hardware basics: inside the box

Hardware Basics:
Inside the Box
Miguel Rebollo

Introduction to Computer Science
2009-2010

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


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

Basic components
Storage

Input devices: Output devices:
keyboard screen, printer,
and mouse speakers
CPU

Memory


Von Newman archit.

CPU

system i/o bus
input/output
bus(*)

memory

(*) front side bus

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)


Bits as numbers

There are only
10 types of people in the world:
those who understand binary
and those who don’t


Binary number system
decimal binary
• All numbers as 0 000
combinations of two
digits: 0 and 1 (base 2) 1 001
2 010
• conversion 3 011
binary-decimal 4 100
5 101
• with n digits we have 2n
6 110
possibilities
7 111
Play with the numbers

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)

ASCII code

• ASCII code uses 8 bits
• 8 bits produce 2 =256 possibilities
8

• It’s not enough, several codes added
• mutually incompatible
• changes in special letters (ñ, á, ç, ...)


Bits, bytes and
buzzwords
• Bit-related terminology
1 Byte =
1 kilobyte (kB) = 1024 Bytes
1 megabyte (mB) = 1024 kB
1 gigabyte (gB) = 1024 mB
1 terabyte (tB) = 1024 gB
1 petabyte (pB) = 1024 tB
1 exabyte (eB) = 1024 pB
• Other units: Zettabyte,Yottabyte...
• See Data Powers of Ten

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


Evolution of Intel proc.

Intel processor history


CPU equivalence
Intel AMD
Obsolete Pentium 4 Athlon 64
Low-end Celeron Sempron
Core 2 Duo, i3, i5 Athlon 64 x2
Desktop
Core 2 Quad, i5, i7 Phenom
Laptop Centrino, i3, i5 Turion
Netbook Atom -----
Servers/ Xeon Opteron
Workstation Itanium -----


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.

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)


RAM memory
Stores temporally
program instructions and data

• it’s volatile

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


ROM
(read only
memory)
information stored in
chips

contains startup
instructions


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

• Flash memory: used in
phones, PDA or
cameras


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


Hardware basics: inside the box

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