Browse Prior Art Database

CSMA/CD LAN Adapter Transmit Data Error Handler

IP.com Disclosure Number: IPCOM000110017D
Original Publication Date: 1992-Oct-01
Included in the Prior Art Database: 2005-Mar-25
Document File: 5 page(s) / 155K

Publishing Venue

IBM

Related People

Ku, EH: AUTHOR [+4]

Abstract

Fig. 1 is a typical CSMA/CD LAN adapter consisting of a transmit data buffer, a receive data buffer, a CSMA/CD LANC Controller (or LANC processor), a transceiver circuit (or MODEM), a bus arbitration/data error detect logic, and possibly a microprocessor. The transmit data buffer is used to store the packet data to be transmitted. The receive data buffer is used to store the received data from the "remote station" via media/MODEM/LANC Controller. The bus arbitration/error detect logic arbitrates and grants the data bus to bus requests such as LANC Controller TxD DMA requests, RxD DMA requests, microprocessor bus requests, the Host bus requests from the surrounding functional blocks.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 52% of the total text.

CSMA/CD LAN Adapter Transmit Data Error Handler

       Fig. 1 is a typical CSMA/CD LAN adapter consisting of a
transmit data buffer, a receive data buffer, a CSMA/CD LANC
Controller (or LANC processor), a transceiver circuit (or MODEM), a
bus arbitration/data error detect logic, and possibly a
microprocessor.  The transmit data buffer is used to store the packet
data to be transmitted.  The receive data buffer is used to store the
received data from the "remote station" via media/MODEM/LANC
Controller.  The bus arbitration/error detect logic arbitrates and
grants the data bus to bus requests such as LANC Controller TxD DMA
requests, RxD DMA requests, microprocessor bus requests, the Host bus
requests from the surrounding functional blocks.  It also verifies
the data validity and "flags" the transmit data errors and received
data errors (data parity error, data buffer pointer errors, etc.) to
alert the microprocessor and/or the host of the data problem when it
occurred.

      The transmit data (byte format) is first stored in the transmit
data buffer.  The CSMA/CD LANC Controller gets the data from the
transmit data buffer, formats the data (adding PREAMBLE, BOF
delimiter, CRC, EOF delimiter, etc.), serializes and encodes it, then
passes it, to the transceiver for transmission.  The CSMA/CD LANC
adapter receives its own "echoed back" data and verifies the data
validity for transmission collision detect.  If data error is
detected, the transmission ABORT sequence will take place (switch to
sending JAMMING patterns and stop transmit after the completion of
jamming pattern transmission).  The ABORT sequence is important for
the CSMA/CD LANC, since it is an effective way to ensure the
transmitted data packet has an abnormal ending.  That prevents any
receive station from recognizing it as a "GOOD" data packet.

      A typical CSMA/CD LANC Controller has an 8-bit data bus and is
designed to take "good" transmit data from the data bus for
transmission.  Most of the CSMA/CD LANC Controllers do not handle
error c...