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MU9C8K64-90TDI 参数 Datasheet PDF下载

MU9C8K64-90TDI图片预览
型号: MU9C8K64-90TDI
PDF下载: 下载PDF文件 查看货源
内容描述: MU9C RCP家庭 [MU9C RCP Family]
分类和应用: 存储内存集成电路静态存储器双倍数据速率
文件页数/大小: 35 页 / 1040 K
品牌: MUSIC [ MUSIC SEMICONDUCTORS ]
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Register Descriptions  
MU9C RCP Family  
Full Cascading  
Highest-Priority Matching address operate over the entire  
system; only the device in which the /MI line is HIGH and  
that has a match will respond to the cycle. This scheme  
automatically prioritizes a system of vertically cascaded  
devices, the highest up in the chain has the  
highest-priority. Note, however, that cycles that do not  
access highest-priority match data or the Status register  
will operate regardless of the state of the Match daisy  
chain.  
The Full flag is set LOW in a particular MU9C RCP if the  
/FI line is LOW, and that device is full. During a Write  
cycle, the Full flag will not change until /E goes HIGH  
during that cycle. When the /FI line is HIGH, one or more  
locations are free in the higher-priority devices; therefore,  
when the /FI line is HIGH, whether or not that particular  
device is full, its /FF output will remain HIGH. This  
method allows the Full Flag daisy chain to recognize  
non-contiguous empty locations throughout the entire  
MU9C RCP system.  
Multiple Match Flag Daisy Chain  
The Multiple Match flag, /MM, is an open-drain output,  
and will be pulled LOW by a particular device when its  
/MI input is HIGH and there is more than one match  
within the device, or when the /MI input is LOW and there  
is one match within the device. During a Comparison  
cycle, the Multiple Match flag will not change until /E  
goes HIGH during that cycle. This wired-OR output  
provides system level indication of the multiple match  
condition within a vertically cascaded system of MU9C  
RCPs.  
The daisy chain gives System Full indication. When the  
device at the end of the chain has its /FF output LOW, the  
entire CAM system is full. The first device in the daisy  
chain has its /FI line tied LOW to ensure data can be  
written into the system.  
The daisy chain also controls Write at Next Free Address  
cycles as well as Read Next Free Address cycles so that  
they work globally across the system, and not just locally  
in a specific device. Only the device in which the /FI line  
is LOW, and which is not full, will respond to the Write  
cycle. Therefore, deletions and insertions can be made in  
the memory, without the need to keep track of empty  
locations.  
Match Flag Timing Overhead  
There is a propagation delay for the match results to ripple  
down through the daisy chain. All the MU9C RCPs within  
the system execute a Comparison cycle in parallel, so the  
local results are available at the end of a Comparison  
cycle. The local Match flags do not change during a  
Comparison cycle until /E goes HIGH. The logical  
combination of the results then propagates down the daisy  
chain with a delay through each stage. The compare time  
in each device operating in parallel is added to the ripple  
delay through the daisy chain. Before reading the results  
of a comparison from the System Match flag, the daisy  
chain must be given time to settle to a valid state. If there  
are N devices vertically cascaded in a system, and the time  
to get a valid output on /MF for one device is t(MF), and  
the propagation delay for the flag to ripple through one  
device from /MI valid to /MF valid is t(PD), then the time  
t(DC) for the daisy chain to develop a valid output  
condition is:  
Match Cascading  
The Match flag /MF will be LOW in a particular device  
within a vertically cascaded system when its /MI input is  
LOW, or when there is a match in that device. During a  
Comparison cycle, the Match flag will not change until /E  
goes HIGH during that cycle. When the /MI line is LOW,  
one or more locations in higher-priority devices have a  
match; when the /MI line is LOW, the /MF output will be  
forced LOW. This method allows the Match Flag daisy  
chain to respond to and prioritize matches throughout the  
entire MU9C RCP system.  
The daisy chaining gives a System Match indication.  
When the device at the end of the daisy chain has its /MF  
output LOW, there is a match within the MU9C RCP  
system. The first device in the daisy chain has its /MI input  
tied HIGH.  
t(DC) = t(MF)+(N-1)*t(PD)  
This period of time must elapse before the flagged results  
of the comparison are available, and before /OE is driven  
LOW or a Status Register Read cycle is performed.  
The daisy chain also controls access to the device by  
controlling the outputs during a Read Highest-Priority  
Match data, or Read Status register, onto the DQ31-0  
lines. The device must be selected with either /CS1, or  
/CS2, or the Data Select register. After a Comparison or  
Read/Write at Highest-Priority Match Address cycle, only  
the device whose /MI line is HIGH, and which has a valid  
match, will drive data onto DQ31-0 or onto PA:AA bus;  
any device that has its /MI line set LOW will have its  
outputs in their high-impedance state, even if it has a valid  
match. Therefore, Reads from and Writes to the  
There is a similar but shorter delay for the Full Flag daisy  
chain, but this only limits the rate at which back-to-back  
Write at Next Free Address cycles can be performed.  
Rev. 8.04  
15  
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