Sander Sassen van HardwareCentral heeft een artikel geschreven over de nieuwste technologie van Rambus, Quad Rambus Signaling Level. De voorloper hiervan, RSL, wordt al in de RDRAM modules gebruikt. RSL was één van de eerste toepassingen van DDR. QRSL laat een dubbel zo grote bandbreedte als RSL toe, zonder de kloksnelheid van het geheugen te verhogen. Het is een nogal technisch verhaal, maar hier een opsomming van de kenmerken van QRSL:
Low-voltage swing, 800mV pp, ~267mV per step
Current mode output drivers
Automatic output current control, for three drive levels
Controlled impedance design, typically 40 Ohms
Double date rate, multi-level signaling, four bits per clock-cycle
Bi-directional channel, multiple data bits outstanding
Pseudo-differential signals, three Vref inputs
Integrated advanced driver and receiver circuitsCommon differential clock, travels with data and loops around in the controller
Terminated at one end[break]De conclusie is als volgt:[/break]Rambus' QRSL multilevel signaling is a third technique for doubling bandwidth. Its main advantage is that it can be used on the same printed circuit boards, built with the same manufacturing technology, and can be tested with current test equipment used to test RSL signaling technology.
QRSL's first commercial debut is still unknown, but we might be seeing some of it in memory products. However, Intel will not be using QRSL with its upcoming Willamette CPU. However, QRSL test systems have already been demostrated, and the technology has been in development since 1997. Rambus Inc. is currently in the process of working with major OEMs and semiconductor partners to move this technology from the lab into commercial products.
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