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Using APEX 20KE Fast Search Applications
Altera Corporation Innovation Drive Jose, 95134 (408) 544-7000 http://www.altera.com https://websupport.altera.com
APEX20KE embedded system blocks (ESBs) support content-addressable memory (CAM), parallel processing memory that accelerates applications requiring fast searches through databases, lists, patterns. memory technology developed from RAM. Most other memory devices store retrieve data addressing specific memory locations. However, CAM, system supplies data receives data's address, shown Figure
Figure APEX Integrated
When using CAM, system supplies data, returns address.
When using RAM, system supplies address, returns data.
Data Address Match Flag Address
High
Address Data
APEX 20KE offers ideal solution high-performance applications such data compression, network switches, Internet protocol filters, peripheral component interconnect (PCI) functions. addition performance advantages, integrated APEX 20KE devices provides flexible sizes. Figure illustrates typical applications using various block sizes.
Altera Corporation
M-TB-056-01
Using APEX 20KE Fast Search Applications
Figure APEX Offers Flexible Block Sizes
Width
APEX 20KE Discrete (Fixed Sizes)
1,024 8,192 2,048 4,096 4,096 16,384
Small-Sized Applications Switch Address Mapping Packet Header Identification Pattern Recognition Internet Protocol Filter Cache
Medium-Sized Applications Address Look-Up Layer Bridges Switches Address Translation Protocol Conversion Gateways Layer Longest Match Address Look-up IPv4, DECNET Appletalk VPI/VCI Translation ASwitches
Large-Sized Applications Cache Network Server Layer Flow Recognition Fair Bandwidth Sharing Layer Address Caching IPv6 Switch
Depth
Memory Search Applications
Memory applications, which often involve searching, have previously been implemented programmable logic devices (PLDs) using RAM. Searching item take many clock cycles. latency search depends depth block; 64-word 32-bit block requires clock cycles find data. Identifying item stored memory data content rather than address more efficient. works this way, making ideal high-speed search applications. simultaneously compares data requested against list entries, providing order magnitude reduction search time over RAM. Other memory algorithms, such binary- tree-based searches, look-aside buffers, perform multi-cycle search through memory space much slower than CAM. better understand performance advantages CAM, compare total time required search item using both implementations. Locating item 32-word 32-bit block running requires clock cycles 8-ns clock cycle). contrast, total time required find item similar-sized block cycle 4-ns clock cycle). faster than latency clock cycle compared maximum cycles RAM.
Altera Corporation
Using APEX 20KE Fast Search Applications
APEX Integration Enhances Performance
Traditionally, search applications discrete CAM, where implemented separate device. designer must individual device printed circuit board (PCB), which increases design time reduces amount usable space. Discrete also reduces system performance because introduces additional onand off-chip delays. APEX provides higher performance than discrete eliminating off-chip board delays. Also, APEX CAM-which manufactured 0.18-µm process-has much faster access time than typical discrete CAM, which generally manufactured older processes, resulting slower access time ns). Figure illustrates system performance advantages APEX over discrete CAM.
Figure APEX Integrated Provides Superior Performance
Discrete System Performance
Register
APEX System Performance APEX 20KE-1 Discrete
Register Register
Register
tACC 20.0
Delay
Delay 20.0 28.2
applications that require block larger than what available APEX 20KE device, embedded APEX cache larger, discrete block. This implementation APEX 20KE accelerates large applications, shown Figure APEX that interfaces with system finds match clock cycle, system immediately proceeds. Otherwise, system waits three clock cycles external find match, then proceeds.
Figure APEX Cache Large, Discrete
APEX 20KE Device
100-MHz System Data tLAD Data Address Address Address Data
Large External
tACC 20.0
Altera Corporation
Using APEX 20KE Fast Search Applications
APEX Provides Flexibility
APEX offers variable sizes. APEX configured 32-word 32-bit block, multiple ESBs cascaded together implement wider deeper blocks. create depth width long there additional unused ESBs. example, ESBs EP20K1500E device used CAM, create 228-Kbit block with varying widths depths (e.g., 7,296 words bits 3,648 words bits). Table lists APEX resources available.
Table APEX Device Densities Resources
Feature
Maximum System Gates Logic Elements ESBs Maximum Bits
EP20K60E EP20K100E EP20K160E EP20K200E EP20K300E EP20K400E EP20K600E EP20K1000E EP20K1500E
162,000 2,560 16,384 263,000 4,160 26,624 404,000 6,400 40,960 526,000 8,320 53,248 728,000 11,520 73,728 1,052,000 1,537,000 16,640 106,496 24,320 155,648 1,772,000 38,400 163,840 2,524,000 54,720 233,472
Conclusion
APEX family first offer integrated PLD. This advanced feature provides system performance benefits designers simplifying functions that require searches through lists data tables. With additional benefits enhanced system performance, effective resource utilization, inherent configuration flexibility, APEX devices offer spectrum block sizes, providing superior integration benefits over competing devices.
Innovation Drive Jose, 95134 (408) 544-7000 http://www.altera.com
Copyright 1999 Altera Corporation. Altera, APEX, APEX 20K, APEX 20KE, EP20K60E, EP20K100E, EP20K160E, EP20K200E, EP20K300E, EP20K400E, EP20K600E, EP20K1000E, EP20K1500E trademarks and/or service marks Altera Corporation United States other countries. Other brands products trademarks their respective holders. specifications contained herein subject change without notice. Altera assumes responsibility liability arising application information, product, service described herein except expressly agreed writing Altera Corporation. Altera customers advised obtain latest version device specifications before relying published information before placing orders products services. rights reserved.
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