Appendix A: Data Sheet Revision History ........................................................................................................................................... 81
The Microchip Web Site ...................................................................................................................................................................... 82
Customer Change Notification Service ............................................................................................................................................... 82
Customer Support ............................................................................................................................................................................... 82
Product Identification System ............................................................................................................................................................. 83
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1.0
1.1
INTRODUCTION
General Terms and Conventions
The host interface function that performs code conversion,
buffering, and the like required for communications to and
from a network.
A packet containing ports, addresses, etc. to make sure
data being passed through a bridged network arrives at its
proper destination.
A common semiconductor manufacturing technique in
which positive and negative types of transistors are com-
bined to form a current gate that in turn forms an effective
means of controlling electrical current through a chip.
A common technique for detecting data transmission
errors. CRC for Ethernet is 32 bits long.
A switch typically processes received packets by reading in
the full packet (storing), then processing the packet to
determine where it needs to go, then forwarding it. A cut-
through switch simply reads in the first bit of an incoming
packet and forwards the packet. Cut-through switches do
not store the packet.
The address to send packets.
A design in which memory on a chip is controlled inde-
pendently of the CPU.
A design in which memory on a chip can be erased by
exposing it to an electrical charge.
A bus architecture designed for PCs using 80x86 proces-
sors, or an Intel 80386, 80486 or Pentium microprocessor.
EISA buses are 32 bits wide and support multiprocessing.
A naturally occurring phenomena when the electromag-
netic field of one device disrupts, impedes or degrades the
electromagnetic field of another device by coming into
proximity with it. In computer technology, computer devices
are susceptible to EMI because electromagnetic fields are
a byproduct of passing electricity through a wire. Data lines
that have not been properly shielded are susceptible to
data corruption by EMI.
See CRC.
Specifies the frame identifier. Alternately is the filter identi-
fier.
The following is list of the general terms used throughout this document:
BIU - Bus Interface Unit
BPDU - Bridge Protocol Data Unit
CMOS - Complementary Metal Oxide
Semiconductor
CRC - Cyclic Redundancy Check
Cut-Through Switch
DA - Destination Address
DMA - Direct Memory Access
EEPROM - Electronically Erasable
Programmable Read-Only Memory
EISA - Extended Industry Standard
Architecture
EMI - Electro-Magnetic Interference
FCS - Frame Check Sequence
FID - Frame or Filter ID
IGMP - Internet Group Management Protocol
The protocol defined by RFC 1112 for IP multicast trans-
missions.
IPG - Inter-Packet Gap
A time delay between successive data packets mandated
by the network standard for protocol reasons. In Ethernet,
the medium has to be "silent" (i.e., no data transfer) for a
short period of time before a node can consider the net-
work idle and start to transmit. IPG is used to correct timing
differences between a transmitter and receiver. During the
IPG, no data is transferred, and information in the gap can
be discarded or additions inserted without impact on data
integrity.
The disruption of transmitted code caused by adjacent
pulses affecting or interfering with each other.
ISI - Inter-Symbol Interface
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ISA - Industry Standard Architecture
Jumbo Packet
A bus architecture used in the IBM PC/XT and PC/AT.
A packet larger than the standard Ethernet packet (1500
bytes). Large packet sizes allow for more efficient use of
bandwidth, lower overhead, less processing, etc.
An Ethernet port connection that allows network hubs or
switches to connect to other hubs or switches without a
null-modem, or crossover, cable. MDI provides the stan-
dard interface to a particular media (copper or fiber) and is
therefore 'media dependent.'
An Ethernet port connection that allows networked end sta-
tions (i.e., PCs or workstations) to connect to each other
using a null-modem, or crossover, cable. For 10/100 full-
duplex networks, an end point (such as a computer) and a
switch are wired so that each transmitter connects to the
far end receiver. When connecting two computers together,
a cable that crosses the TX and RX is required to do this.
With auto MDI-X, the PHY senses the correct TX and RX
roles, eliminating any cable confusion.
The MIB comprises the management portion of network
devices. This can include things like monitoring traffic lev-
els and faults (statistical), and can also change operating
parameters in network nodes (static forwarding
addresses).
The MII accesses PHY registers as defined in the IEEE
802.3 specification.
An expansion board inserted into a computer to allow it to
be connected to a network. Most NICs are designed for a
particular type of network, protocol, and media, although
some can serve multiple networks.
The port VLAN ID value is used as a VLAN reference.
An electronic circuit that controls an oscillator so that it
maintains a constant phase angle (i.e., lock) on the fre-
quency of an input, or reference, signal. A PLL ensures
that a communication signal is locked on a specific fre-
quency and can also be used to generate, modulate, and
demodulate a signal and divide a frequency.
An occurrence that affects the directing of power to differ-
ent components of a system.
Manages packet traffic between MAC/PHY interface and
the system host. The QMU has built-in packet memories
for receive and transmit functions called TXQ (Transmit
Queue) and RXQ (Receive Queue).
The address from which information has been sent.
TDR is used to pinpoint flaws and problems in under-
ground and aerial wire, cabling, and fiber optics. They send
a signal down the conductor and measure the time it takes
for the signal—or part of the signal—to return.
Commonly a cable containing 4 twisted pairs of wires. The
wires are twisted in such a manner as to cancel electrical
interference generated in each wire, therefore shielding is
not required.
A configuration of computers that acts as if all computers
are connected by the same physical network but which
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