Pin Descriptions
MU9C4320L ATMCAM
PA3–0 (Page Address, Output)
The PA3–0 lines convey Page Address information. When
the /OE input is HIGH, the PA3–0 outputs are in their
high-impedance state; when /OE is LOW the PA3–0 lines
carry the Page Address value held in the Configuration
register. The PA3–0 lines are latched when /E is LOW, and
are free to change only when /E is HIGH. The Page
Address value of the currently active or highest-priority
responding device is output at the same time, and under
the same conditions, as the AA11–0 lines are active.
/AV (Address Valid, Input)
When Hardware control is selected, the /AV input
determines whether the AC11–0 lines carry address or
control information. When /AV is LOW, the AC11–0 lines
convey a memory address; when /AV is HIGH, the
AC11–0 lines convey control information. The state of the
/AV line is registered by the falling edge of /E. When
software control is selected, the /AV line distinguishes
between instructions and data on the DQ31–0 lines; when
/AV is LOW, data is present on the DQ31–0 lines; when
/AV is HIGH, an instruction is present on the DQ11–0
lines.
/E (Chip Enable, Input)
The /E input is the main chip enable and synchronizing
control for the ATMCAM. When /E is HIGH, the chip is
disabled and the DQ31–0 lines are held in their
high-impedance state. The falling edge of /E registers the
/W, /CS1, /CS2, /AV, /AC11–0 lines, and the /VB and
DQ31–0 lines for a Write cycle. /E being LOW causes the
results of the previous comparison or memory access to be
latched on the PA3–0:AA11–0 lines; when /E goes HIGH
the latches open allowing the new comparison results or
random access memory address to flow to the
PA3–0:AA11–0 lines.
/VB (Validity Bit, Three-state, Common
Input/Output)
During accesses over the DQ31–0 lines, the /VB line
conveys validity information to and from the ATMCAM.
During a Write cycle (/W=LOW), when /VB is LOW the
addressed location is set valid; when /VB is HIGH it is set
empty. During a Read cycle (/W=HIGH), the validity of
the addressed location is read on the /VB line. During a
Write cycle, the state of the /VB line is registered by the
falling edge of /E.
/CS1, /CS2 (Chip Select 1, Chip Select 2,
Inputs)
The /CS1 and /CS2 inputs enable the ATMCAM. If either
/CS1 or /CS2 are LOW, the device is selected for a Read,
Write, or Compare cycle through the DQ31–0 lines, or for
an internal data transfer. The /CS1 and /CS2 lines do not
have any effect on the PA3–0:AA11–0 outputs. The state
of the /CS1 and /CS2 lines is registered by the falling edge
of /E.
/MF (Match Flag, Output)
The /MF output indicates whether a valid match has
occurred during the previous Comparison cycle. If the
/MF output is HIGH at the end of a Comparison cycle,
then no match occurred; if it is LOW then either a match
occurred within the device, or the /MI input is LOW,
conditioned by the /MF output from a higher-priority
device in the system. The /MF line is used in conjunction
with the /MV line to indicate when a match occurred in the
CAM array or the VP Table. If /MF is LOW, then the
match occurred in the CAM array; if /MF is HIGH and
/MV is LOW, then the match occurred in the VP Table.
Both /MF and /MV lines are HIGH after a Compare cycle
that results in a mismatch. The state of the /MF line will
not change until after the rising edge of /E during the
Comparison cycle. Note that /MF indicates the results of
the most recent Comparison cycle; it will not change when
the PA3–0:AA11–0 lines carry an address other than the
Match address.
/W (Write Enable, Input)
The /W input determines the direction of data transfer on
the DQ31–0 lines during Read, Write, and Data Move
cycles. When /W is LOW, data flows into the DQ31–0
lines; when /W is HIGH, data flows out. The /W line also
conditions the control state present on the AC11–0 lines.
The state of the /W line is registered by the falling edge of
/E.
/OE (Output Enable, Input)
The /OE input enables the PA3–0:AA11–0 outputs. When
/OE is HIGH, PA3–0:AA11–0 are in their high-impedance
state. When /OE is LOW, PA3–0:AA11–0 outputs are
active, and convey the results of the last Comparison
Cycle Match address or Memory Access address. In a
vertically cascaded system, only the PA3–0:AA11–0
outputs of the highest-priority device will be activated by
/OE being LOW; in lower-priority devices, the
PA3–0:AA11–0 outputs remain in high impedance
regardless of the state of /OE.
Rev. 3
/MI (Match Input, Input)
The /MI input receives match information from the next
higher-priority ATMCAM in a vertically cascaded system
to provide system-level prioritization. When the /MI input
is HIGH, the /MF output will only go LOW if there is a
match during a Comparison cycle; when the /MI input is
LOW, the /MF output will go LOW. The /MF output from
one device is connected to the /MI input of the next
lower-priority device. The /MI pin of the highest-priority
device must be tied HIGH.
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