All SATA devices operate independently of each other. The transfer rate is governed chiefly by the device speed, and each device can operate simultaneously at that speed. Contrast that to PATA devices, where the maximum speed of devices attached to a single cable is that of the slowest attached. In addition, delays (and effective reduction in speed) are caused when both devices on the cable need to be accessed (only one device can utilise the interface at a time, the other device has to wait until the interface becomes free). In all cases, drivers
and CPU/memory speed throughput are also a factor.