Quad data rate (or quad pumping) is a communication signaling technique wherein data are transmitted at four points in the clock cycle: on the rising and falling edges, and at two intermediate points between them. The intermediate points are defined by a 2nd clock that is 90° out of phase from the first. The effect is to deliver four bits of data per signal line per clock cycle.
In a quad data rate system, the data lines operate at twice the frequency of the clock signal. This is in contrast to double data rate systems where the clock and data lines operate at the same frequency.
QDR technology was introduced by Intel in their Willamette core Pentium 4 CPU, and is currently employed in their Atom, Pentium 4, Celeron, Pentium D, and Core 2 Processor ranges. This technology has allowed Intel to produce chipsets and microprocessors that can communicate with each other at data rates expected of the traditional FSB technology running from 400 MT/s to 1600 MT/s, while maintaining a lower and thus more stable actual clock frequency of 100 MHz to 400 MHz.
Famous quotes containing the words data and/or rate:
“Mental health data from the 1950’s on middle-aged women showed them to be a particularly distressed group, vulnerable to depression and feelings of uselessness. This isn’t surprising. If society tells you that your main role is to be attractive to men and you are getting crow’s feet, and to be a mother to children and yours are leaving home, no wonder you are distressed.”
—Grace Baruch (20th century)
“We all run on two clocks. One is the outside clock, which ticks away our decades and brings us ceaselessly to the dry season. The other is the inside clock, where you are your own timekeeper and determine your own chronology, your own internal weather and your own rate of living. Sometimes the inner clock runs itself out long before the outer one, and you see a dead man going through the motions of living.”
—Max Lerner (b. 1902)