ICS1893BY-10 - Release
Chapter 3 Overview of the ICS1893BY-10
3.1 100Base-TX Operation
During 100Base-TX data transmission, the ICS1893BY-10 accepts packets from a MAC/repeater and
inserts Start-of-Stream Delimiters (SSDs) and End-of-Stream Delimiters (ESDs) into the data stream. The
ICS1893BY-10 encapsulates each MAC/repeater frame, including the preamble, with an SSD and an ESD.
As per the ISO/IEC Standard, the ICS1893BY-10 replaces the first octet of each MAC preamble with an
SSD and appends an ESD to the end of each MAC/repeater frame.
When receiving data from the medium, the ICS1893BY-10 removes each SSD and replaces it with the
pre-defined preamble pattern before presenting the nibbles to its MAC/Repeater Interface. When the
ICS1893BY-10 encounters an ESD in the received data stream, signifying the end of the frame, it ends the
presentation of nibbles to its MAC/Repeater Interface. Therefore, the local MAC/repeater receives an
unaltered copy of the transmitted frame sent by the remote MAC/repeater.
During periods when MAC frames are being neither transmitted nor received, the ICS1893BY-10 signals
and detects the IDLE condition on the Link Segment. In the 100Base-TX mode, the ICS1893BY-10 transmit
channel sends a continuous stream of scrambled ones to signify the IDLE condition. Similarly, the
ICS1893BY-10 receive channel continually monitors its data stream and looks for a pattern of scrambled
ones. The results of this signaling and monitoring provide the ICS1893BY-10 with the means to establish
the integrity of the Link Segment between itself and its remote link partner and inform its Station
Management Entity (STA) of the link status.
For 100M data transmission, the ICS1893BY-10 MAC/Repeater Interface can be configured to provide
either a 100M Media Independent Interface (MII) or a 100M Symbol Interface. With the Symbol Interface
configuration, the data stream bypasses the ICS1893BY-10 Physical Coding sublayer (PCS). In addition:
1. The ICS1893BY-10 shifts the responsibility of performing the 4B/5B translation to the MAC/repeater.
As a result, the requirement is for a 5-bit data path between the MAC/repeater and the ICS1893BY-10.
2. The latency through the ICS1893BY-10 is reduced. (The ICS1893BY-10 provides this 100M Symbol
Interface primarily for repeater applications for which latency is a critical performance parameter.)
3.2 10Base-T Operation
During 10Base-T data transmission, the ICS1893BY-10 inserts only the IDL delimiter into the data stream.
The ICS1893BY-10 appends the IDL delimiter to the end of each MAC frame. However, since the 10Base-T
preamble already has a Start-of-Frame delimiter (SFD), it is not required that the ICS1893BY-10 insert an
SSD-like delimiter.
When receiving data from the medium (such as a twisted-pair cable), the ICS1893BY-10 uses the
preamble to synchronize its receive clock. When the ICS1893BY-10 receive clock establishes lock, it
presents the preamble nibbles to its MAC/Repeater Interface. The 10M MAC/Repeater Interface can be
configured as either a 10M MII, a 10M Serial Interface, or a Link Pulse Interface.
In 10M operations, during periods when MAC frames are being neither transmitted nor received, the
ICS1893BY-10 signals and detects Normal Link Pulses. This action allows the integrity of the Link Segment
with the remote link partner to be established and then reported to the ICS1893BY-10’s STA.
ICS1893BY-10 Rev A 3/24/04
March, 2004
Copyright © 2004, Integrated Circuit Systems, Inc.
All rights reserved.
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ICSI [ INTEGRATED CIRCUIT SOLUTION INC ]
