cache Last modified: Thursday, September 16, 2004
Pronounced cash, a special high-speed storage mechanism. It can be either a reserved section of main memory or an independent high-speed storage device. Two types of caching are commonly used in personal computers: memory caching and disk caching. A memory cache, sometimes called a cache store or RAM cache, is a portion of memory made of high-speed static RAM (SRAM) instead of the slower and cheaper dynamic RAM (DRAM) used for main memory. Memory caching is effective because most programs access the same data or instructions over and over. By keeping as much of this information as possible in SRAM, the computer avoids accessing the slower DRAM. Some memory caches are built into the architecture of microprocessors. The Intel 80486 microprocessor, for example, contains an 8K memory cache, and the Pentium has a 16K cache. Such internal caches are often called Level 1 (L1) caches. Most modern PCs also come with external cache memory, called Level 2 (L2) caches. These caches sit between the CPU and the DRAM. Like L1 caches, L2 caches are composed of SRAM but they are much larger. Disk caching works under the same principle as memory caching, but instead of using high-speed SRAM, a disk cache uses conventional main memory. The most recently accessed data from the disk (as well as adjacent sectors) is stored in a memory buffer. When a program needs to access data from the disk, it first checks the disk cache to see if the data is there. Disk caching can dramatically improve the performance of applications, because accessing a byte of data in RAM can be thousands of times faster than accessing a byte on a hard disk. When data is found in the cache, it is called a cache hit, and the effectiveness of a cache is judged by its hit rate. Many cache systems use a technique known as smart caching, in which the system can recognize certain types of frequently used data. The strategies for determining which information should be kept in the cache constitute some of the more interesting problems in computer science.
•E-mail this definition to a colleague• Sponsored listings Internet Caching - Find Cache Solutions and Compare prices at Shopica.com. Search products and stores before making a purchase. Start Now! Local Insurance Agents in Cache - Find and compare local insurance agents and quotes from major carriers. Average U.S. policy is $60.75/mo. GlobalSpec.com: Computer Memory - Provides database of suppliers for computer memory. Includes catalogs, technical information, and supplier contact information. For internet.com pages about cache . Also check out the following links! BIOS Settings - Advanced Chipset Features  Extensive information on the settings associated with fine-tuning control over the system cache, memory, and I/O buses, to optimize performance. This page is from "The PC Guide". Caching Tutorial for Web Authors and Webmasters  A must read for anyone interested in Web caches. PC secondary cache reference guide  Looks at the secondary cache on the PC motherboard. Describes how the cache works in detail. Discusses cache characteristics, timing, technology types, packaging, and structures. "Layers" of Cache Description of Level 2 and 3 cache, as well as disk and peripheral cache. This page is from "The PC Guide". Cache and the Web Digital and the National Library for Applied Network Research (NLANR) are working together to create a national architecture for handling highly popular information (the internet). This page describes that effort, as well as provides numerous links to this work and research. Cache Characteristics Describes the different features of the level 2 cache. This page is from "The PC Guide". Cache Structure and Packaging Describes the different types of packaging that cache is normally found in. Includes information about integrated Level 2, daughterboard, and motherboard cache, as well as COASt (Cache On A Stick) modules. This page is from "The PC Guide". Cache Transfer Technologies and Timing Describes the factors that directly influence the performance of the level 2 cache, including cache bursting and pipeline burst cache. Also included is information on system timing and a comparison of transfer technology. This page is from "The PC Guide". Function and Operation of the System Cache Discusses the principles behind the design of cache memory, and explains how the secondary (level 2) cache works in detail. This page is from "The PC Guide". Managing Netscape cache Provides several tips for controlling the amount of disk space set aside for the Netscape browser's cache. What is a cache? Describes what level two cache is and how it works. Sponsored listings Computer Memory - Broad-line distributor web site features real-time stock status and pricing, online ordering, RFQ, technical support, product datasheets and photos. Used and Refurbished Cisco Equipment - Buys and sells used and refurbished network equipment, including Cisco routers, switches, security devices, GSR's, LOcal Directors, and memory. Computer Memory - Offers a full range of computer memory including Apple, Compaq, Cisco, Dell and Gateway. DSP Design : eLearning - Free Registration. By Industry Leaders for Electronics Professionals. Computer Memory at Dell Business- Official Site - Check out Dell Small Business for Computer Memory. Buy Dell Direct.	Caches Performance buffer buffer underrun CDN CELP COAST connection pool disk cache main memory pipeline burst cache proxy cache RAM disk snooping protocol tag RAM write-back cache Give Us Your Feedback Shopping cache Products Compare Products,Prices and Stores Shop by Category: Processors 286 Model Matches Hard Drives 255 Model Matches Laptops 123 Model Matches Cache Memory 80 Model Matches PC Desktops 99 Model Matches