WidePort LANCAM® Family
PIN DESCRIPTIONS Continued
/RESET (Reset, Input, TTL)
VCC, GND (Positive Power Supply, Ground)
These pins are the power supply connections to the
WidePort LANCAM. VCC must meet the voltage supply
requirements in the Operating Conditions section relative
to the GND pins, which are at 0 Volts (system reference
potential), for correct operation of the device. All the
ground and power pins must be connected to their
respective planes with adequate bulk and high frequency
bypassing capacitors in close proximity to the device.
The MU9C2485A/L and MU9C1485A/L are compatible
with the original MU9C1485 connections, and may be
operated at -90 or slower switching characteristics
without the GND connections on pins 1, 2, 20, 21, 22, 41,
42, 60, 61, and 62.
/RESET must be driven LOW to place the device in a known
state before operation, which will reset the device to the
conditions shown in Table 5. The /RESET pin should be
driven by TTL levels, not directly by an RC timeout. /E
must be kept HIGH during /RESET.
TEST1, TEST2 (Test, Input, TTL)
These pins enable MUSIC production test modes that are
not usable in an application. They should be connected to
ground, either directly or through a pull-down resistor, or
they may be left unconnected. These pins may not be
implemented on all versions of these products.
FUNCTIONAL DESCRIPTION
The WidePort LANCAM is a content-addressable
memory (CAM) with 32-bit I/O for network address
filtering, virtual memory, data compression, caching, and
table lookup applications. The memory consists of static
CAM, organized in 64-bit data fields. Each data field can
be partitioned into a CAM and a RAM subfield on 16-bit
boundaries. The contents of the memory can be randomly
accessed or associatively accessed by the use of a
compare. During automatic comparison cycles, data in
the Comparand register is automatically compared with
the “Valid” entries in the memory array. The Device ID can be
read using a TCO PS instruction (see Table 13).
globally configurable into CAM and RAM segments on
16-bit boundaries, as described in US Patent 5,383,146
assigned to MUSIC Semiconductors. Seven different
CAM/RAM splits are possible, with the CAM width
going from one to four segments, and the remaining RAM
width going from three to zero segments. Finer resolution
on compare width is possible by invoking a mask register
during a compare, which does global masking on a bit
basis. The CAM subfield contains the associative data,
which enters into compares, while the RAM subfield
contains the associated data, which is not compared. In
LAN bridges, the RAM subfield can hold, for example,
port-address and aging information related to the
destination or source address information held in the
CAM subfield of a given location. In a translation
application, the CAM field can hold the dictionary
entries, while the RAM field holds the translations, with
almost instantaneous response.
The data inputs and outputs of the WidePort LANCAM
are multiplexed for data and instructions over a 32-bit
I/O bus. Internally, data is handled on a 64-bit basis,
since the Comparand register, the mask registers, and
each memory entry are 64 bits wide. Memory entries are
/W
/CM
Cycle Type
“f” Bit
DQ31–16
DQ15–0
XXXX
LOW
LOW
Command write
0
1
Non-TCO Instruction
Non-TCO Instruction
Absolute Address
XXXX
0
TCO Instruction (Read register)*
TCO Instruction (Write register)
Status Register bits 31–16
Status Register bits 31–16†
Data to CR, MRX, Mem.
1
Value to Register
Status Register bits 15–0
Register contents*
Data to CR, MRX, Mem.
Data from CR, MRX, Mem.
HIGH
LOW
Command read
TCO 2nd cycle
Data write
X
X
X
X
LOW
HIGH
HIGH
HIGH
Data read
Data from CR, MRX, Mem.
*
Notes:
A CW of a TCO Instruction with the “f” bit set to 0 sets up a Register read in the following cycle. The
following cycle must be a Command Read cycle, otherwise the register read will be cancelled.
†
Upper 16 bits will be Status Register bits 31–16, except for a read of the Page Address register, in which
case they will be all zeros.
Table 3: DQ Bus Multiplexing
4
Rev. 2
MUSIC [ MUSIC SEMICONDUCTORS ]
