
56 The Essential Guide to Serial ATA and SATA Express
2.7.3 Parallel ATA Emulation
Emulation of parallel implementations of ATA device behavior as perceived by the host BIOS or soft-
ware driver is a cooperative effort between the device and serial interface host adapter hardware. The
behavior of Command and Control Block registers, PIO and DMA data transfers, resets, and interrupts
are all emulated.
The host adapter contains a set of registers that Shadow the contents of the traditional device regis-
ters (see Figure 2.13), referred to as the Shadow Command Block and Shadow Control Block.
The Command Block registers are used for sendin