1.\" $OpenBSD: atapiscsi.4,v 1.11 2007/05/31 19:19:49 jmc Exp $ 2.\" 3.\" Copyright (c) 1999 Constantine Sapuntzakis. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 4. Neither the name of the University nor the names of its contributors 14.\" may be used to endorse or promote products derived from this software 15.\" without specific prior written permission. 16.\" 17.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 18.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 19.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 20.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 21.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 22.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 23.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 24.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 25.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 26.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 27.\" SUCH DAMAGE. 28.\" 29.Dd $Mdocdate: May 31 2007 $ 30.Dt ATAPISCSI 4 31.Os 32.Sh NAME 33.Nm atapiscsi 34.Nd ATAPI<->SCSI adapter 35.Sh SYNOPSIS 36.Cd "atapiscsi* at wdc? flags 0x0000" 37.Cd "atapiscsi* at pciide? flags 0x0000" 38.Cd "scsibus* at atapiscsi?" 39.Sh DESCRIPTION 40The 41.Nm 42driver supports ATAPI (also called IDE) devices such as CD-ROMs, ZIP 43drives, LS-120 floppy drives, and tape drives. 44All ATAPI devices talk a subset of the SCSI protocol. 45.Pp 46The 47.Nm 48driver acts like a SCSI adapter. 49Thus, the ATAPI devices connected to the system will appear as SCSI devices. 50ATAPI CD-ROMs will appear as 51.Xr cd 4 52devices, ATAPI tape drives as 53.Xr st 4 54devices, and ATAPI floppies as 55.Xr sd 4 56devices. 57.Pp 58For performance reasons, one should avoid putting an ATAPI device and 59a hard disk on the same cable. 60The driver does not support bus release and, even if it did, many ATAPI 61devices do not support it. 62There is only one command outstanding on a cable at a time. 63For example, if a hard disk and a CD drive are placed on the same cable, 64the hard disk requests may get queued behind slower CD operations. 65.Pp 66The 67.Cm flags 68are used only with controllers that support DMA operations and 69mode settings (like some 70.Xr pciide 4 71controllers). 72The lowest order (rightmost) nibble of the 73.Cm flags 74define the PIO mode to use. 75The next four bits indicate the DMA mode and the third nibble the UltraDMA 76mode. 77.Pp 78For each set of four bits, the 3 lower bits define the mode to use 79and the last bit must be set to 1 for this setting to be used. 80For DMA and UltraDMA, 0xf (1111) means 81.Dq disable . 82For example, a 83.Cm flags 84value of 0x0fac (1111 1010 1100) 85means 86.Do 87use PIO mode 4, DMA mode 2, disable UltraDMA 88.Dc . 89The special setting 0x0000 means 90.Dq use whatever the drive claims to support . 91.Sh SEE ALSO 92.Xr cd 4 , 93.Xr intro 4 , 94.Xr pciide 4 , 95.Xr scsi 4 , 96.Xr sd 4 , 97.Xr st 4 , 98.Xr wdc 4 99.Sh BUGS 100Slow devices, like tape drives, could do a better job of sharing the channel. 101For now, we recommend you put the tape device on its own channel. 102