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Despite sounding related, QDR and DDR are mostly unrelated technologies. They are also both poorly named. The real purpose of DDR is not actually to double the
by ATsch 6y ago
Despite sounding related, QDR and DDR are mostly unrelated technologies. They are also both poorly named.
The real purpose of DDR is not actually to double the data rate, but to halve your clock speed and allow you to use the same frequency for your clock as your data. This mostly benefits signal integrity.
QDR is better understood as memory with two ports, one for reading and one for writing, which can be used at the same time. This is a lot more expensive and really doesn't have huge benefits for PCs compared to just adding more channels (as DDR5 does).
- Dylan16807 6y agoWell there's "QDR" memory like you describe, and then there's "QDR" like GDDR5X and GDDR6 have, which is a single port doing 4 transfers per clock. That said DDR5 is solidly on two transfers per clock, so I don't understand the suggestion to call it or use "QDR2" (what's QDR1 for contrast?).
- ATsch 6y agoQDR/QDR2 are real interfaces, although for SRAM. Afaict Micron and Cypress make them for specialialty applications.