Motherboards are the foundation for every PC. You should be very
familiar with system board architecture and be able to recognize most
components. Components to be able to identify include:
CPU
Real-time Clock and CMOS battery
BIOS chip
Switch connectors
Cache
IDE and floppy connectors
All expansion slots and types
Memory banks and types
Power connectors
All integrated ports, including video (AGP)
Terminology
System Chipset: the logic circuits for system functions like
caching and interrupting. The chipset will affect the processor type, speed
and multitasking, the amount of RAM and L2 cache supported, and power
management.
Controller Chips: Keyboard and PS/2 mouse controllers, I/O port
controllers, EIDE and floppy drive controllers, and any other built-in
interfaces (like sound, network)
Clock:Handles multiple speeds with the clock multiplier
I/O Ports: usually 2 serial, 1 parallel, 2 USB, 2 PS/2 (keybd,
mouse), 2 internal EIDE, 1 internal floppy port
Memory Slots: SIMM or DIMM, or both
Level 2 Cache: usually a DIP chip or COASt (Cache on a stick), a
dedicated high-speed backside bus (DIB – Dual Independent Bus)
architecture.
Form Factors: the shape and physical size of the system board: AT,
baby AT, ATX, mini ATX, LPX, and mini-LPX, NLX.
Bus: buses are a common medium for the transfer of data from one
location, device, or component to another.
Also called Impact printers (parts actually impact the paper)
Fires pins (or print wires) at an ink ribbon, which contacts the
paper and leaves a mark
The print head, the assembly which contains the pins, moves left to
right across the paper, line by line, creating letters out of the circular
dots of ink that have impacted he paper.
Coils of wires called solenoids are energized, thus creating an
electromagnet, and cause the pins to shoot forward and strike the ribbon.
Print quality is measured in "pins", as in 9-pin, 24-pin, 48-pin
printers: number of pins in the print head.
The quality of print is at best NLQ, Near Letter Quality.
The speed of the printer is measured in cps, characters per second.
The paper most often used with dot matrix is continuous, tractor-fed paper
with perforated strips on the sides.
This printer uses pin feeders and tractor feeders with this paper to
prevent skewing. The roller (or platen) applies pressure (friction)
when you use plain paper to keep the paper from slipping. If you are using
multiple-copy paper, you can adjust the platen gap to the thickness
of the paper.
Dot matrix printers are rather expensive to purchase now because they
serve the niche multiple-copy stationary market, and so many companies want
old ones fixed.
Inkjet Printers
Inkjet printers use liquid ink-filled cartridges that force out and spray
ink at the page through tiny holes called nozzles.
The printer sprays ink at the page through pressure and electricity.
Normally, the pressure inside the ink cartridge (in the ink reservoir)
is a bit less than pressure outside. When the deflection plates are
electrically charged, ink is forced out.
Inkjet printers have two kinds of print heads that move back and forth in
perfect synchronization with the spray of ink. HPs
have thermal-shock print heads, which have a heating element around
each nozzle that, when heated, causes the ink to expand. Epson
printers have piezoelectric (electrostatic) print heads that, when
charged, changes the size and shape of the nozzle, and acts like a pump.
Inkjet printers can use plain paper and inkjet specific paper (for higher
print quality).
Print quality is measured in dpi, dots per inch.
Print speed is measured in ppm, pages per minute.
Laser Printers
The majority of businesses (including BrainBuzz here) use laser
printers for demanding printing needs (speed, quantity, quality).
Laser printers print one whole page at a time, and require RAM (more
memory) to operate.
Print quality is measured as dpi
When the printer receives the print data for a page, it breaks the data
into single-dot strips called rasters (this is called rasterizing,
amazingly enough).
Sharing resources and information (printing, files)
Access: dial-up using modem, ISDN, DSL, cable, leased lines
How a Network Works
Networks are made up of three basic components:
Protocols – rules of communication
Transmission media – methods for interconnecting network elements
Network Services – shared resources
Networks are either peer-to-peer or server-based.
Peer-to-peer:
Doesn’t require dedicated resources: any host can share its resources
with any other host on the network
Less expensive, easier to work/maintain, less secure, fewer users (less
than 10)
File system management problems
Windows for Workgroups 3.x/95/98
Server-based:
Configuration of nodes. A dedicated node that shares out its resources to
hosts is a server (resources like printers, files, and applications)
More security, more expensive
Print servers, file servers, mail servers, web servers
Novell NetWare, UNIX, Microsoft NT/2000, Apple AppleTalk
Physical Topologies:
Bus
Star
Ring
Mesh: every computer is connected to every other computer Hybrid: any of these in combination Token Ring: (or star-wired ring) uses a MAU
and token passing to ensure only one device is communicating at a time (FDDI
uses token passing)
Do not confuse Physical Topologies with Logical Topologies.
Logical Topology: the actual path of a signal over a
network (bus, ring)
Physical topologies: how the network devices are actually
connected.
Network Operating Systems:
Novell NetWare 5
Microsoft NT, 2000
UNIX
Networking Components
NIC (Network Interface Card), also called an adapter card:
interface between a single computer and the network
Repeater: an amplifier that prevents signal degradation over
distance
Hub: a focal point of a network – connects computers in a
physical star topology
Switches: device for filtering frames and connecting segments of a
network, uses MAC addresses
Routers: direct data packets between networks using IP addresses
Brouters: combination bridge and router
Bridges: directs information flow on a network from one node to
another.
Gateway: converts protocols
Modem (Modulate/Demodulate): a device to connect computers over
analog telephone lines.
Cables
Fiber Optic cables are the fastest, most expensive, and most difficult to
implement
Single-mode: specific wavelength
Multi-mode: many wavelengths (frequencies, or modes)
Twisted Pair cannot exceed 100 m
STP: shielded twisted pair
UTP: unshielded twisted pair
Category
Description
1
Voice (UTP only)
2
4 twisted pairs, data
transmission up to 4 Mbps (UTP only), token ring
3
4 twisted pairs, data
transmission up to 10 Mbps, Ethernet
4
4 twisted pairs, data
transmission up to 16 Mbps, token ring
5
4 twisted pair, data
transmission up to 100 Mbps, Ethernet and fast Ethernet
6
4 twisted pair, data
transmission up to 155 Mbps, fast Ethernet
7
4 twisted pair, data
transmission up to 1000 Mbps, gigabit Ethernet
Connectors
RJ-45 (like phone jack)
Coaxial/BNC (Thicknet, Thinnet) (like cable TV)
Transmission Types
Synchronous: transmissions are synchronized between the access
devices and the network device (message-framed data), and the message is
received in the order it was transmitted.
Asynchronous: transmissions are asynchronized between the access
device and the network device, but each character is synchronized by
information in the header and trailer bits.
Data transmission flow: circuits are:
Simplex: one direction
Half duplex: two directions, only one at a time
Full duplex: two directions simultaneously.
Baseband: entire media bandwidth for a single channel using TDM
(Time Division Multiplexing)
Broadband: divides media bandwidth into multiple channels, each
with a separate signal using FDM (Frequency Division Multiplexing)
Networking Issues
Slowdown
Bandwidth
Cost
Maintenance
Traffic demands
Hardware
Install and configuring a NIC
Network Interface Cards move data between a local computer and
the network.
Types of NICs include:
ISA
PCI
PCMCIA
Note: know how to install and configure a NIC, and also how to
share resources.
Shared Folder
Shared Drive
Mapped Drive
Special Thanks to Cherina
Sparks MA, A+
for contributing this Cramsession.
Visit her site
