Digital Sound

Computer Sound

• To convert an analog wave into digital, converters use a process called sampling

• DEF: Sampling- the height of the sound wave is sampled at regular intervals of time (fractions of a sec)

Sound Compression --MP3

• Music is sampled 44,100 times per second.

• Separate samples are taken for the left and right speakers in a stereo system.

• The goal of the MP3 format is to compress a CD-quality song by a factor of 10 to 14 without losing the CD-quality sound.

MP3• The MP3 compression algorithm makes use

of limited human perception• If you were think of an algorithm to

compress sound, how would you go about eliminating bytes?

• Why is MP3 a good compression algorithm?

A byte can also be part of a computer program

• A computer program is a sequence of instructions in the machine language of the computer– Move (move a byte from disk to memory, or

from memory to the printer)– Add – add two binary numbers– Compare – check two binary numbers for

equality, greater than, or less than

Computer Hardware

• Next two weeks, we’ll be covering Computer hardware

– Goals• Conceptually understand how the HW of a

computer works • How to be a better PC customer/consumer.

The Progression of a computer’s “ease of use”

• 1950’s

• 1960’s - 1970’s

• 1980’s - today

• Why was this good?

Computer Hardware’s Basic Function

• All about manipulating binary data

Hardware has the Components that…

• Process data • Store the data • Communicate the data • Input data • Output data

How We Process & Store Data (CPU)– blue

Basic internals of a computer box

CPU’s QualitiesCentral Processing Unit

Yesterdays Processor• The first microprocessor was the Intel 4004,

introduced in 1971.

• Prior to the 4004, engineers built computers either from:– collections of chips– discrete components (transistors wired one at a

time).

• The Home Computer had a microprocessor called the Intel 8080– Intel 8080 was a complete 8-bit (which

means what?) computer chip, introduced 1974.

Yesterdays Processor

Examples of CPUs on Today’s Market

Pentium III/IV is a CPU, or “processor” made by Intel

Celeron is a less expensive, slower processor made by Intel

PowerPC is a processor made by Motorola and is the basis of the Macintosh

Today’s Processor• Made of Chips of silicon • Your desktop computer has a CPU chip that is

made of silicon. – Silicon is a semiconductor material ( partial

resistance to electricity)– It is mounted on a carrier– It has metal pins that plug into the motherboard

• Remember: computer understands electrical impulses, silicon is conducive to this

Processors 2 main components

Another Hardware Component

CLOCK

Clock Speed

• Speeds of the Clock are measured in?

• What do we mean by an 800 MHz processor

• Today, clock speeds go into the GHz

Clock Speed vs. Computer Speed

• Question: Why can’t I crank up my processor to 100mhz?

Clock Speed

• True: The clock controls the speed of which operations inside the CPU are happening

• True: the larger the CPU speed, the faster the computer can be

• True: The CPU speed is dependent and can only be as fast as the other supporting computer hardware

• True: Bottlenecks inhibit speed

Parameters that limit speed

• Transmission delays on the chip – How other hardware components are

interacting with the clock

• Heat buildup on the chip.

Bus- red

MOTHERBOARD

Ports