Analysis of information sources in references of the Wikipedia article "Quad data rate" in Portuguese language version.
In both DDRs and QDRs, the read and write signals are transferred on both the rising and falling edges of the clock. This increases the frequency with which the device can be used. But in DDR, there is only one data bus which transfers the read and writes data (common I/O), unlike in QDRs where there are two separate I/O buses for data transfers. Hence in QDRs it is possible to transfer four words of data in one clock cycle, unlike two in double data rate.
QDR (Quad Data Rate)
Externamente o Pentium M trabalha igual o Pentium 4 transferindo quatro dados por pulso de clock, fazendo com que o barramento local tenha um desempenho quatro vezes maior do que seu clock atual. Esta técnica é chamada de Quad Data Rate.
QDR Taxa de Dados Quadruplicada (do original Quad Data Rate)
