XRT79L71 Datasheet, PDF (271/441 Pages) Exar Corporation – 1 - CHANNEL DS3/E3 ATM UNI/PPP COMBO IC

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PRELIMINARY
1 - CHANNEL DS3/E3 ATM UNI/PPP COMBO IC
XRT79L71
REV. P1.0.3
BIT NUMBER
NAME
TYPE
DESCRIPTION
1
Receive Cell Insertion R/O Receive Cell Insertion Memory - ROOM Indicator:
Memory ROOM
This READ-ONLY bit-field indicates whether or not there is room (e.g.,
empty space) available for the contents of another ATM cell to be written
into the Receive Cell Insertion Memory.
0 - Indicates that the Receive Cell Insertion Memory does not contain
enough empty space to receive another ATM cell via the Microprocessor
Interface.
1 - Indicates that the Receive Cell Insertion Memory does contain
enough empty space to receive another ATM cell via the Microprocessor
Interface.
NOTE: The user should verify that the Receive Cell Insertion Memory
has sufficient empty space to accept another ATM cell of data
(via the Microprocessor Interface) by polling the state of this bit-
field prior to writing each cell into the Receive Cell Insertion
Memory.
0
Receive Cell Insertion W/O Receive Cell Insertion Memory - Write SOC (Start of Cell):
Memory WSOC
Whenever the user is writing the contents of an ATM cell into the
Receive Cell Insertion Memory, then he/she is suppose to identify/des-
ignate the very first byte of this ATM cell by setting this bit-field to "1".
Whenever the user does this, then the Receive Cell Insertion Memory
will "know" that the next octet that is written into the "Receive ATM Cell
Processor Block - Receive Cell Insertion/Extraction Memory Data Reg-
ister - Byte 3 (Address = 0x1714) is designated as the first byte of the
ATM cell currently being written into the Receive Cell Insertion Memory.
This bit-field must be set to "0" during all other WRITE operations to the
Receive ATM Cell Processor - Receive Cell Insertion/Extraction Memory
Data Register.
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