L9 Memory - Computer Science 230H Memory Prepared by...

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Computer Science 230H Memory Prepared by Michael Jack Fall 2007 Slides set 1
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Memory 2 References The information and figures for the following slides were prepared from the following source: Patterson, D., and Hennessy J., Computer Organization and Design, 3rd edition, 2005 Stallings, W., Computer Organization and Architecture: Designing for Performance 7 th edition, 2006 Hircock B., Computer Science 230 Course Notes
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Memory 3 Introduction
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Memory 4 Processor processing speeds are much faster than memory access time. Basic Problem Year Performance 1 10 100 1,000 10,000 100,000 CPU Memory Design challenge: dealing with this growing disparity.
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Memory 5 Historically, the limiting factor in a computer’s performance has been memory access time – Memory speed has been slow compared to the speed of the processor. – A process could be bottlenecked by the memory system’s inability to “keep up” with the processor – Why? Basic Problem (cont)
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Memory 6 Location Performance Processor Access time Internal (main) Cycle time External (secondary) Transfer rate Capacity Physical Type Word size Semiconductor Number of words Magnetic Unit of Transfer Optical Word Magneto-Optical Block Physical Characteristics Access Method Volatile/nonvolatile Sequential Erasable/nonerasable Direct Organization Random Associative Characteristics of Computer Memory Systems
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Memory 7 Word – The “natural” unit of memory organization. – The size of the world is typically equal to the number of bits used to represent an integer and to the instruction length. Addressable unit – The fundamental data element size that can be addressed in the memory. – Might either be a word or a byte. – The relationship between the length in bits A of an address and the number N of addressable units is 2 A = N . Unit of transfer – The number of data elements transferred at a time. – Usually words between CPU and cache, blocks between cache and memory, pages between memory and secondary storage. Characteristics of Computer Memory Systems
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Memory 8 Sequential access – Memory is organized into units of data, called records. – Access is made in a specific linear sequence. Direct access – Data items have unique addresses. – Access is done using a combination of moving to a general memory “area” followed by a sequential access to reach the desired data item. – Example: disk drives. Random access – Each addressable location in memory has a unique physical address. – Locations can be accessed in any order and all access times are the same. – Example: main memory. Characteristics of Computer Memory Systems
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Memory 9 Associative access – A variation of random access memory. – Data items are accessed based on their contents rather than their actual
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This note was uploaded on 02/14/2010 for the course COMPUTER S COIS-3030 taught by Professor Hircock during the Spring '10 term at Trent University.

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L9 Memory - Computer Science 230H Memory Prepared by...

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