IDT72P51749L6BBI8 IDT, Integrated Device Technology Inc, IDT72P51749L6BBI8 Datasheet - Page 33

• Manufacturer Part Number: IDT72P51749L6BBI8
• Description: IC FLOW CTRL 36BIT 256-BGA
• Manufacturer: IDT, Integrated Device Technology Inc

Specifications of IDT72P51749L6BBI8

• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: 72P51749L6BBI8

QUEUE MARKing
write and/or re-read information that is stored into a queue.
operation is port independent. The same queue can be marked by the write port
and the read port simultaneously. Only the active queue can be MARKed,
multiple queues can NOT be MARKed by a port. A port (write or read) may only
designate one queue MARKed at a time. Upon a queue switch a decision must
be made as to whether to return to the Marked location or the last access address.
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IDT72P51749/72P51759/72P51769 1.8V, MULTI-QUEUE FLOW-CONTROL DEVICES
(128 QUEUES) 36 BIT WIDE CONFIGURATION 1,179,648, 2,359,296, and 4,718,592
bits
The overall intent of the MARK function is to provide the ability to either re-
A queue can be MARKed by either the write port or the read port. The MARK
@QS-1, if WEN=0 and WADEN=1, PQ will be updated in QS0,1, and 2, and NQ data will be written in QS3.
@QS-1, if WEN_N=1 and WADEN=1, there is no update for PQ during QS0-QS2. Next time PQ is switched back, data will be written into last update
location (rewrite).
@QS0, WADEN status is used to determine if a “mark” is requested for NQ. If WADEN=1 in QS0, NQ will be marked. In FIFO mode, the first NQ
position after QS is marked (latch WFCR values before QS3), data can’t be read out beyond this location. In packet mode, every SOP position is
marked till next SOP comes, then the mark moves to new position.
@QS0, if WADEN=0, NQ is not marked.
@QS-1 (A), if REN=0 and RADEN=1, (request for a Queue Switch occurs RADEN=1 and simultaneously reading from a queue) the Queue Address
Register will be updated in QS2, and the data from the Next Queue (NQ) will be available in QS3.
@QS-1, if REN=1 and RADEN=1, (request for a Queue Switch occurs RADEN =1) the Queue Address Register will be updated in QS2. The Present
Queue address pointer will not increment during QS0-QS2. The Next time PQ is selected, the data will be from the last addressed location.
@QS0, RADEN status is used to determine if a “mark” is requested for NQ. If RADEN=1 in QS0, NQ will be mark. In FIFO mode, first NQ position after
QS is marked (latch RFCR values before QS3), data can’t overwrite this location. In packet mode, every SOP position is marked till next SOP comes,
then the mark moves to new position.
RADEN
RCLK
QOUT
REN
WADEN
WCLK
WEN
DIN
QS
QS
QS-1
QS-1
A
A
Figure 13. MARK and Re-Write Sequence
Figure 14. MARK and Re-Read Sequence
Present Queue
QS0
QS0
Present Queue (PQ)
B
B
QS1
QS1
C
C
QS2
33
QS2
D
MARK AND REWRITE/ MARK AND REREAD
IDT Standard Mode, FIFO Mode, FWFT Mode), FWFT). Queues on the Write
Port are MARKed using the WCLK &
Port are MARKed using the RCLK and RADEN signals. Refer to the following
timing diagrams for additional queue MARK details. Refer to Figure 13 through
18 for further information.
D
The MARK functionality operates in any mode combination (Packet mode,
QS3
E
QS3
E
Next Queue (NQ)
Next Queue
COMMERCIAL AND INDUSTRIAL
WADEN signals. Queues on the Read
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TEMPERATURE RANGES
FEBRUARY 10, 2009
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