SDRAM Memory: DRAM And Beyond - Industry Trend or Event

Computer Technology Review, August, 1999 by Stuart Atkins

In late 1996, Rambus agreed to a development and license contract with Intel that will lead to Intel's PC chip sets, supporting Rambus memory starting in late 1999. Currently, the Nintendo 64 video game utilizes Rambus technology for 3D graphics and CD audio. Standard PCs from Gateway and Micron in addition to add-in PC cards from companies, like Creative Labs, use Rambus memory.

DIRECT RAMBUS

Direct Rambus technology is an extension of today's RDRAMs. Direct RDRAMs use the same signaling (RSL: Rambus Signaling Level), but have a wider interface (16 bits), higher frequency at 800MHz, and improved protocol ([greater than]90% efficient). A single Direct RDRAM will deliver 1.6GB/sec; two supply 3.2GB/sec. A Direct Rambus uses two 8-bit channels to get 1.6GB and 3 channels to obtain 2.4GB (Table 2).

ANSWER TO THE PERFORMANCE GAP

Only companies that make major investments now in new equipment, technology, and personnel will be able to effectively provide virtual warehousing of SDRAMs, DDR, SLDRAM, and RDRAM memory modules as they emerge between now and the year 2000. The older, Fast Page Mode and Extended Data Out (EDO) memory product technology is much less complex than upcoming memory technologies, as noted in the preceding analysis. The upcoming memory technologies support much higher speed applications where even minute timing incompatibilities can cause major system problems.

Stuart Atkins is the marketing analyst and product manager of Kingston Technology (Fountain Valley, CA).

                                Comparisons
                          DDR                         Concurrent Direct
               SDRAM     SDRAM     SLDRAM     RDRAM     RDRAM    RDRAM
    Peak                                                          1.6
 Bandwidth   125MB/sec 200MB/sec 400MB/sec  600MB/sec 600MB/sec  GB/sec
    MHz       125MHz    200MHz     400MHz    600MHz     600MHz   800MHz
  Standard                         SLDRAM
    Body       JDEC      JDEC    Consortium  Rambus     Rambus   Rambus
Availability   1997      1998       1999      1995       1997     1999
  Voltage      3.3V      3.3V       2.5V      3.3V       3.3V     2.5V
Source: Toshiba and Rambus