MU9C1965A/L LANCAM MP
OPERATIONAL CHARACTERISTICS Continued
automatically masks all 128 bits of data to find all
locations with the validity bits set to “Empty,” while the
other forced compares are only masked as selected in
the Control register.
/E
/EC
VERTICAL CASCADING
/EC (INT)
/MF
LANCAM MPs can be vertically cascaded to increase
system depth. Through the use of flag daisy-chaining,
multiple devices will respond as an integrated system.
The flag daisy chain allows all commands to be issued
globally, with a response only in the device containing
the Highest-Priority Matching or Next Free location. When
connected in a daisy chain, the last device’s Full flag and
Match flag accurately report the condition for the whole
string. A system in which LANCAM MPs are vertically
cascaded using daisy-chaining of the flags is shown in
Figure 1a on page 7.
Figure 5: /EC(Int) Timing Diagram
The minimum timings for the /E control signal are given in
the Switching Characteristics section on page 26. Note that
at minimum timings the /E signal is non-symmetrical, and
that different cycle types have different timing requirements,
as given in Table 8 on page 22.
To operate the daisy chain, the Device Select registers are
set to FFFFH to enable all devices to execute Command
Write and Data Write cycles. In normal operation, read
cycles are enabled from the device with the highest-priority
match by locking the daisy chain (see the “Locked Daisy
Chain” section). An individual device in the chain may be
targeted for a read or write operation by temporarily setting
the Device Select registers to the Page address of the target
device. Setting the Device Select registers back to FFFFH
restores the operation of the entire daisy chain.
COMPARE OPERATIONS
During a Compare operation, the data in the Comparand
register is compared to all locations in the Memory array
simultaneously. Any mask register used during compares
must be selected beforehand in the Control register. There
are two ways compares are initiated: Automatic and Forced
compares.
Match Flag Cascading
Automatic compares perform a compare of the contents of the
Comparand register against Memory locations that are tagged
as “Valid,” and occur whenever the following happens:
The Match Flag daisy chain cascading is used for three
purposes: first, to allow operations on Highest-Priority
Match addresses to be issued globally over the whole
string; second, to provide a system wide Match flag;
third, to lock out all devices except the one with the
Highest-Priority match for instructions such as Status
reads after a match. The Match flag logic causes only
the highest-priority device to operate on its Highest-
Priority Match location while devices with lower-priority
matches ignore Highest-Priority Match operations. The
lock-out feature is enabled by the match flag cascading
and the use of the /EC control signal, as shown in Tables
6a and 6b on page 12.
Ø The Destination Segment counter in the Segment
Control register reaches its end limit during writes to
the Comparand or mask registers.
Ø After a command write of a TCO CT is executed (except
for a software reset), so that a compare is executed
with the new settings of the Control register.
Forced compares are initiated by CMP instructions
using one of the four validity conditions, V, R, S, and E.
The forced compare against “Empty” locations
15
Rev. 1a
MUSIC [ MUSIC SEMICONDUCTORS ]
