MCM67T415 Datasheet, PDF (1/3 Pages) Motorola, Inc – 16K x 15 Bit Cache Tag RAM for Pentium Processors

MOTOROLA
SEMICONDUCTOR TECHNICAL DATA
Order this document
by MCM67T415/D
Advance Information
16K x 15 Bit Cache Tag RAM
for Pentium™ Processors
MCM67T415
The MCM67T415 is a 245,760 bit cache–tag static RAM designed to support
Pentium microprocessors at bus speeds up to 66 MHz. It is organized as 16K words
of 15 bits each and is fabricated using Motorola‘s high performance, silicon gate
BiCMOS technology. There are twelve common I/O tag bits and three separate I/O
status bits. A 12–bit comparator is on–chip to allow fast comparison of the 12 stored
tag bits with the current tag input data. An active high MATCH output is generated
when the valid bit is true and these two groups of data are the same for a given
address.
This high–speed MATCH signal, with tAVMV times as fast as 9 ns, provides the
fastest possible enabling of secondary cache accesses.
The three separate I/O status bits (VALID, DIRTY, and WT) can be configured for
either dedicated or generic functionality, depending on the SFUNC input pin. With
SFUNC low, the status bits are defined and used internally by the device, allowing
easier determination of the validity and use of the given tag data. SFUNC high
releases the defined internal status bit usage and control, allowing users to
configure the status bit information to fit their system needs. A synchronous RESET
pin, when held low at a rising clock edge, will reset all status bits in the array for easy
invalidation of all tag addresses.
The MCM67T415 also provides the option for burst ready (BRDY) generation
within the cache tag itself, based upon MATCH, VALID bit, WT bit, and other external
inputs provided by the user. This can significantly simplify cache controller logic and
minimize cache decision time. Match and read operations are both asynchronous
in order to provide the fastest access times possible, while write operations are
synchronous for ease of system timing.
The MCM67T415 uses a 5 V power supply on VCC and VSS, with separate VCCQ
pins provided for the outputs to offer compliance with both 5 V TTL and 3.3 V LVTTL
logic levels. The PWRDN pin offers a low–power standby mode, which provides
significant system power savings.
The MCM67T415 is offered in a space saving 80–pin thin quad flat pack (TQFP)
package.
• 16K x 15 Configuration:
– 12 Tag Bits
– Three Status Bits (Valid, Dirty, and WT)
• Valid Bit used to Qualify Match Output
• High–Speed Address–to–Match Comparison Times – 9/10/12 ns
• BRDY Circuitry Included Inside the Cache–Tag for the Highest Speed
Operation
• Asynchronous Read/Match Operation and Synchronous Write and Reset
Operation
• Separate Write Enable for Tag Bits and Status Bits
• Separate Output Enable for Tag Bits, Status Bits, and BRDY
• Synchronous RESET Pin for Invalidation of all Tag Entries
• Dual Chip Selects for Easy Depth Expansion with No Performance
Degradation
• I/O Pins Both 5 V TTL and 3.3 V LVTTL Compatible with VCCQ Pins
• PWRDN Pin to Place Device in Low–Power Mode
• Drop–In Replacement for IDT71215
• Packaged in an 80–Pin Thin Quad Flat Pack (TQFP)
Pentium is a trademark of Intel Corp.
This document contains information on a new product. Motorola reserves the right to change or discontinue this product without notice.
9/10/96
TQ PACKAGE
TQFP
CASE 917A–02
M^© O^MoT^toO^roR^la,O^InL^c.A¹⁹F⁹⁶AST SRAM
MCM67T415
1