Transcript Sound

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 Qualities
Central 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).
Yesterdays Processor
• The Home Computer had a microprocessor
called the Intel 8080
– Intel 8080 was a complete 8-bit (which
means what?) computer chip, introduced
1974.
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
M
O
T
H
E
R
B
O
A
R
D
Ports