Transcript The Visible PC

The Visible PC
Chapter 1
Central Processing Unit (CPU)
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also called “microprocessor”
performs all the calculations that take
place inside a PC
have a cooling fan
have a make and model
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Intel Pentium / AMD Athlon, etc.
CPU’s (continued)
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measure potential performance with a
clock speed measured in megahertz
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first CPU - 4.77 MHz
today CPU - 1000 MHz = 1GHz
come in different packages
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Pin Grid Array (PGA) * most common
Single Edge Cartridge (SEC)
Random Access Memory
(RAM)
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stores programs and data currently
being used by the CPU
measured in units called bytes or
megabytes
average PC will have from 32 - 128 MB
DIMM’s and SIMM’s
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Dual Inline Memory Module
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most common today - 168 pin
Single Inline Memory Module
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basically obsolete
RAM (continued)
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2 most common sizes of SIMM’s
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30 pin and 72 pin
3 most common sizes of DIMM’s
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168 pin
2 Small Outline DIMM’s 72 and 144 pin
(used for laptops mostly)
Motherboard
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“chassis of an automobile”
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everything connects directly or indirectly to
it
thin, flat piece of circuit board
contains sockets and connectors for
various components of the PC
use tiny wires called “traces” to connect
the various components
Motherboard (continued)
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use multipurpose expansion slots to add
optional components
expansion cards plug into the expansion
slots
Power Supply
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provides the necessary electrical power
takes 110-volt AC power and converts it
into 12-volt, 5-volt, and 3.3-volt DC
power
Floppy Drives
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two types of floppy drives
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connects via a 34-pin ribbon cable
floppy cables are unique in 2 ways
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3.5 inch (common) / 5.25 inch (old)
narrowest ribbon cable (approx. 1.5 in. wide)
has a twist in the middle
they need power so they have a
connector which attaches to the power
supply
Hard Drive
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store programs and data that are not
currently being used
capacity measured in megabytes like
RAM
cap. can vary from 500 MB - 75 GB
average PC will have 1 HD but can
accept up to 4
Hard Drives (continued)
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2 common types of HD’s
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EIDE and SCSI
95% of PC’s use EIDE although both
can coexist in one
EIDE - 40 pin, 2 in. cable
SCSI - 50 pin, 2.5 in. cable
SCSI can connect many different
devices and will be discussed in detail
later
CD-ROM Drive
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used to have their own special
controllers
now they run on EIDE or SCSI
controllers
most PC’s have an EIDE hard drive and
a EIDE CD-ROM Drive on one controller
Connectors
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although PC’s use 50 different
connectors, almost all connectors fit
into one of seven major types:
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DB
DIN
Centronics
RJ
- BNC
- audio
- USB
Connectors
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DB Connectors
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have a slight “D” shape
can have from 9 to 37 pins, but rarely
more than 25
can be male/female
DIN Connectors
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2 sizes: DIN and mini-DIN
always female
Connectors
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Centronics
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also “D” shaped, but have a large central tab and
contacts instead of pins
have wings to lock in place
rarely see in back of PC, but almost every printer
in existence has 36-pin socket
RJ Connectors
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RJ-11 - used for modems
RJ-45 - used for network cabling
Connectors
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BNC Connectors
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commonly referred to as coax connector
slowly fading, most PC’s use RJ-45 now
similar to the connection on back of your
TV
Audio Connectors
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used exclusively on sound cards and are
exactly like the plug for headphones on a
walkman
Connectors
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Universal Serial Bus (USB) Connectors
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distinctive rectangular shape
devices are hot-swappable
allows you to daisy-chain up to 127 devices
FireWire Connectors
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also known as IEEE 1394
moves data at incredibly high speeds
making popular for streaming video
Sound Cards
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perform 2 functions
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take digital information and turn it into sound
take sound that is input and turn it into digital
all sound cards have jacks for speakers
and a microphone, and a line-in and
line-out
most provide a 15 pin DB socket that
enables you to attach an instrument or
joystick
also can connect to CD-ROM
Video and Network Cards
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Video Cards
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15-pin female DB connector, 3 rows of pins
nothing else like it on the back of PC
Network Cards
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will have one or more of the following
types of connectors: RJ-45, BNC, 15-pin 2
row female DB, or 9-pin fem. DB
Keyboard / Mouse / Modem
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Keyboard
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Mouse
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2 main types AT DIN and PS/2 style mini DIN
2 sizes: 25-pin (older) / 9-pin (most common)
many PC’s use USB for the mouse so there’s not
excessive cable lying around in the PC
Modem
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external and internal
have 2 RJ-11 sockets
Printer / Joystick
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Printer
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Use a parallel port as opposed to serial
use a 25-pin female DB connector
Joystick
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use a 15-pin female DB connector
originally used as a mouse, now just used
for games
Jumpers and Switches
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Jumpers - tiny pins, usually half a
centimeter long
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shunts connect pins to create a circuit
jumpers without a shunt - open or off
jumpers with a shunt - closed or on
if a shunt is on only one pin and not
connecting it is considered parked
Jumpers and Switches
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Switches
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same thing as jumpers but you don’t have
to worry about losing the shunts
use a small screwdriver or a mechanical
pen to flip the switches, not a pencil or pen
there is no industry standard for jumpers
and switches so you must read the
documentation on the particular PC to
know which one is which