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ITEC 325

ITEC 325. Lecture 30 Memory (7). Review. P2 assigned Exam 2 Friday Paging Segmentation. Flash Memory. • (a) External view of flash memory module and (b) flash module internals. (Source: adapted from HowStuffWorks.com.). Cell Structure.

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ITEC 325

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  1. ITEC 325 Lecture 30 Memory(7)

  2. Review • P2 assigned • Exam 2 Friday • Paging • Segmentation

  3. Flash Memory • • (a) External view of flash memory module and (b) flash module internals. (Source: adapted from HowStuffWorks.com.)

  4. Cell Structure • • Current flows from source to drain when a sufficient negative charge is placed on the dielectric material, preventing current flow through the word line. This is the logical 0 state. When the dielectric material is not charged, current flows between the bit and word lines, which is the logical 1 state.

  5. Rambus • Anyone remember this technology? • Quote: At the 400 MHz databus, the interface to a RDRAM operates with an extremely fine timing granularity of 1.25ns, resulting in a component latency of 38.75ns. The PC100 SDRAM interface runs with a coarse timing granularity of 10ns, or about eight (8) times that of RDRAM. Its interface timing matches the memory core timing very well, therefore its component latency ends at 40ns. The PC133 SDRAM interface, with its coarse timing granularity of 7.5ns, incurs a mismatch with the timing of the memory core. This mismatch significantly increases the component latency to 45ns. http://www.dewassoc.com/performance/memory/rdram_v_sdram.htm

  6. Speed • Rambus was “technically” better • Rambus transferred up to 6400 MB/s • DDR transfers up to 3200 MB/S • DDR2 transfers up to 8533 MB/S • DD3 transfers up to 17,066 MB/s • Corporate decisions • Licensing cost • Manufacturing costs

  7. How • Wide versus small • Send 32 to 64 bits over the bus at a time • Send 8 bits across several times • Rambus = 1.5 inches of Mobo space • SDRAM = 6 inches of Mobo space • Required change in manufacturing process • Problem • Scaling to a 64 bit architecture would be a nightmare

  8. Rambus Memory • • Comparison of DRAM and RDRAM configurations.

  9. Usage • • Rambus technology on the Nintendo 64 motherboard (left) enables cost savings over the conventional Sega Saturn motherboard design (right). • • Nintendo 64 game console:

  10. Summary • Flash memory • RDRAM

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