XRT79L71 Datasheet, PDF (274/441 Pages) Exar Corporation – 1 - CHANNEL DS3/E3 ATM UNI/PPP COMBO IC

XRT79L71
REV. P1.0.3
PRELIMINARY
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1 - CHANNEL DS3/E3 ATM UNI/PPP COMBO IC
RECEIVE ATM CELL PROCESSOR BLOCK - RECEIVE CELL INSERTION/EXTRACTION MEMORY DATA
- BYTE 1 (ADDRESS = 0X1716)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Receive Cell Insertion/Extraction Memory Data[15:8]
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
0
0
0
0
0
0
0
0
BIT NUMBER
NAME
7-0
Receive Cell Insertion/
Extraction Memory
Data[15:8]
TYPE
DESCRIPTION
R/W Receive Cell Insertion/Extraction Memory Data[15:8]:
These READ/WRITE bit-fields, along with that in the "Receive ATM
Cell Processor Block - Receive Cell Insertion/Extraction Memory
Data - Bytes 3, 2 and 0" support the following functions.
a. They function as the address location, for which the user to
write the contents of an "outbound" ATM cell into the Receive
Cell Insertion Memory, via the Microprocessor Interface.
b. They function as the address location, for which the user to
read out the contents of an "inbound" ATM cell from the
Receive Cell Extraction Memory, via the Microprocessor
Interface.
NOTES:
1. If the user performs a WRITE operation to this (and the
other three address locations), then he/she is writing ATM
cell data into the Receive Cell Insertion Memory.
2. If the user performs a READ operation to this (and the other
three address locations, then he/she is reading ATM cell
data from the Receive Cell Extraction Memory.
3. READ and WRITE operations must be performed in a "32-
bit" (4-byte "word") manner. Hence, whenever the user
performs a READ/WRITE operation to these address
locations, he/she must start by writing in or reading out the
first byte (of this "4-byte" word) of a given ATM cell, into/from
the "Receive ATM Cell Processor Block - Receive Cell
Insertion/Extraction Memory - Byte 3 register. Next, the
user must perform a READ/WRITE operation (with the
second of this "4-byte" word) to the "Receive ATM Cell
Processor Block - Receive Cell Insertion/Extraction Memory
- Byte 2 register. Afterwards, the user must perform a
READ/WRITE operation (with the third of this "4-byte" word)
to this register. Finally, the user must perform a READ/
WRITE operation (with the fourth of this "4-byte" word) to the
"Receive ATM Cell Processor Block - Receive Cell Insertion/
Extraction Memory - Byte 0. When reading out (writing in)
the next four bytes of a given ATM cell, the user must repeat
this process with a READ or WRITE operation to the
"Receive ATM Cell Processor Block - Receive Cell Insertion/
Extraction Memory - Byte 3, and so on.
4. Whenever the user is writing cell data into the Receive Cell
Insertion Memory, the size of the Cell is always 56 bytes.
5. Whenever the user is reading cell data from the Receive
Cell Extraction Memory, the size of the Cell is always 56
bytes.
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