1 / 29

AKT211 – CAO 07 – Computer Memory

AKT211 – CAO 07 – Computer Memory. Ghifar Parahyangan Catholic University Okt 24, 2011. Feedback Review. using B. Indonesia for text in the presentation slides make slower and clearer the explanation of the course materials. (x). (v). Outline. Computer Memory System

baakir
Download Presentation

AKT211 – CAO 07 – Computer Memory

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. AKT211 – CAO07 – Computer Memory Ghifar Parahyangan Catholic University Okt 24, 2011

  2. Feedback Review • using B. Indonesia for text in the presentation slides • make slower and clearer the explanation of the course materials (x) (v)

  3. Outline • Computer Memory System • Memory Characteristics • Memory Hierarchy • RAM Basic Technology • Semiconductor • SRAM vs DRAM • Advanced RAM Organization • SDRAM vs DDR-RAM

  4. COMPUTER MEMORY SYSTEM

  5. Characteristics

  6. Location • CPU • Internal • External

  7. Capacity • Word size • The natural unit of organization • Number of words • or Bytes

  8. Unit of Transfer • Internal • Usually governed by data bus width • External • Usually a block which is much larger than a word • Addressable unit • Smallest location which can be uniquely addressed • Word internally • Cluster on M$ disks

  9. Access Methods (1) • Sequential • Start at the beginning and read through in order • Access time depends on location of data and previous location • e.g. tape • Direct • Individual blocks have unique address • Access is by jumping to vicinity plus sequential search • Access time depends on location and previous location • e.g. disk

  10. Access Methods (2) • Random • Individual addresses identify locations exactly • Access time is independent of location or previous access • e.g. RAM • Associative • Data is located by a comparison with contents of a portion of the store • Access time is independent of location or previous access • e.g. cache

  11. Memory Hierarchy • Registers • In CPU • Internal or Main memory • May include one or more levels of cache • “RAM” • External memory • Backing store

  12. Memory Hierarchy - Diagram

  13. RAM BASIC TECHNOLOGY

  14. Semiconductor Main Memory • universally used as RAM basic technology • The basic element : “memory cell” • Read/Write • Volatile • Temporary storage • Static or dynamic

  15. Memory Cell Operation

  16. Semiconductor Memory Types

  17. Dynamic RAM • Bits stored as charge in capacitors • Charges leak • Need refreshing even when powered • Simpler construction • Smaller per bit • Less expensive • Need refresh circuits • Slower • Main memory • Essentially analogue • Level of charge determines value

  18. Dynamic RAM Structure • Address line active when bit read or written • Transistor switch closed (current flows) • Write • Voltage to bit line • High for 1 low for 0 • Then signal address line • Transfers charge to capacitor • Read • Address line selected • transistor turns on • Charge from capacitor fed via bit line to sense amplifier • Compares with reference value to determine 0 or 1 • Capacitor charge must be restored

  19. Static RAM • Bits stored as on/off switches • No charges to leak • No refreshing needed when powered • More complex construction • Larger per bit • More expensive • Does not need refresh circuits • Faster • Cache • Digital • Uses flip-flops

  20. Static RAM Structure

  21. SRAM v DRAM • Both volatile • Power needed to preserve data • Dynamic cell • Simpler to build, smaller • More dense • Less expensive • Needs refresh • Larger memory units • Static • Faster • Cache

  22. ADVANCED RAM ORGANIZATION

  23. Synchronous DRAM (SDRAM) • Access is synchronized with an external clock • Conventional DRAM is asynchronous,CPU must wait the access time delay • With SDRAM, CPU doesn’t have to wait, it can do something else • Takes advantage of the burst mode concept to greatly improve performance • staying on the row containing the requested bit and moving rapidly through the columns, reading each bits as it goes • Idea : most of the time the data needed by the CPU will be in sequence ! • Maximum transfer rate to L2 cache : 528 MBps

  24. SDRAM - Diagram

  25. SDRAM Read Timing

  26. DDR-SDRAM • Double Data Rate Synchronous Dynamic RAM • Higher bandwidth => greater speed • Higher transfer rate • Uses double pumping  transferring data on both the rising and falling edges of the clock signal • Classes : DDR1, DDR2, DDR3 • Neither of which are either forward or backward compatible !

  27. DDR SDRAM Read Timing DDR SDRAM Read Timing

  28. Any Question ?

  29. THANK YOU

More Related