atapiscsi* at wdc? flags 0x0000
atapiscsi* at pciide? flags 0x0000
driver supports ATAPI (also
called IDE) devices such as CD-ROMs, ZIP drives, LS-120 floppy drives, and
tape drives. All ATAPI devices talk a subset of the SCSI protocol.
driver acts like a SCSI
adapter. Thus, the ATAPI devices connected to the system will appear as SCSI
devices. ATAPI CD-ROMs will appear as
devices, ATAPI tape drives as
devices, and ATAPI floppies as
For performance reasons, one should avoid putting an ATAPI device and a hard
disk on the same cable. The driver does not support bus release and, even if
it did, many ATAPI devices do not support it. There is only one command
outstanding on a cable at a time. For example, if a hard disk and a CD drive
are placed on the same cable, the hard disk requests may get queued behind
slower CD operations.
are used only with controllers that
support DMA operations and mode settings (like some
lowest order (rightmost) nibble of the
define the PIO mode to use. The next
four bits indicate the DMA mode and the third nibble the UltraDMA mode.
For each set of four bits, the 3 lower bits define the mode to use and the last
bit must be set to 1 for this setting to be used. For DMA and UltraDMA, 0xf
(1111) means “disable”. For example, a
value of 0x0fac (1111 1010 1100)
means “use PIO mode 4, DMA mode 2, disable UltraDMA”. The
special setting 0x0000 means “use whatever the drive claims to
Slow devices, like tape drives, could do a better job of sharing the channel.
For now, we recommend you put the tape device on its own channel.