MU9C1965L-12TCC 데이터 시트보기 (PDF) - Music Semiconductors

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MU9C1965L-12TCC

LANCAM® MP

Music Semiconductors 

MU9C1965A/L LANCAM® MP

GENERAL DESCRIPTION

The MU9C1965A and MU9C1965L LANCAM® MPs are

1024 x 128-bit content-addressable memories (CAMs),

featuring a 32-bit wide interface. The wide comparand width

allows the LANCAM MP to handle multiple protocols in a

single search table device.

data words up to 128 bits wide allows large address spaces

to be searched rapidly and efficiently. A patented

architecture links each CAM entry to associated data and

makes this data available for use after a successful compare

operation.

Content-addressable memories, also known as associative

memories, operate in the converse way to random access

memories (RAM). In a RAM, the input to the device is an

address and the output is the data stored at that address.

In a CAM, the input is a data sample and the output is a

flag to indicate a match and the address of the matching

data. As a result, a CAM searches large databases for

matching data in a short, constant time period, no matter

how many entries are in the database. The ability to search

The MUSIC LANCAM MP is ideal for address filtering and

translation applications in LAN and ATM switches and

routers that need the wide Comparand for Virtual LANs, VC

translation, or IPV6 address recognition. The 128-bit CAM

width is enough to include the DA, SA, Port ID, and Virtual

LAN ID for LAN switches, or DA, SA, and VC for ATM

switches. The LANCAM MP is also well suited for

encryption, database accelerators, and image processing.

OPERATIONAL OVERVIEW

To use the LANCAM MP, the user loads the data into the

Comparand register, which is automatically compared to all

valid CAM locations. The device then indicates whether

or not one or more of the valid CAM locations contains

data that matches the target data. The status of each CAM

location is determined by two validity bits at each memory

location. The two bits are encoded to render four validity

conditions: Valid, Skip, Empty, and Random access, as

shown in Table 1. The memory can be partitioned into CAM

and associated RAM segments on 32-bit boundaries, but

by using one of the two available mask registers, the CAM/

RAM partitioning can be set at any arbitrary size between

zero and 128 bits.

The LANCAM MP’s internal data path is 128 bits wide for

rapid internal comparison and data movement. Vertical

Skip Bit

0

0

1

1

Empty Bit

0

1

0

1

Entry Type

Valid

Empty

Skip

RAM

Table 1: Entry Types vs. Validity Bits

cascading of additional LANCAM MPs in a daisy chain

fashion extends the CAM memory depth for large

databases. Cascading requires no external logic. Loading

data to the Control, Comparand, and mask registers

automatically triggers a compare. Compares may also be

initiated by a command to the device. Associated RAM

data is available immediately after a successful compare

operation. The Status register reports the results of

compares including all flags and addresses. Two mask

registers are available and can be used in two different

ways: to mask comparisons or to mask data writes. The

random access validity type allows additional masks to be

stored in the CAM array where they may be retrieved

rapidly.

A simple four-wire control interface and commands loaded

into the Instruction decoder control the device. A powerful

instruction set increases the control flexibility and minimizes

software overhead. Additionally, dedicated pins for match

and multiple match flags enhance performance when the

device is controlled by a state machine. These and other

features make the LANCAM MP a powerful associative

memory that drastically reduces search delays.

Rev. 1a

2

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