1.\" $OpenBSD: atapiscsi.4,v 1.7 2001/04/05 20:10:39 deraadt 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 30.Dd July 25, 1999 31.Dt ATAPISCSI 4 32.Os 33.Sh NAME 34.Nm atapiscsi 35.Nd ATAPI<->SCSI adapter 36.Sh SYNOPSIS 37.Cd "atapiscsi* at wdc? channel ? flags 0x0000" 38.Cd "atapiscsi* at pciide? channel ? flags 0x0000" 39.Cd "scsibus* at atapiscsi?" 40.Sh DESCRIPTION 41The 42.Nm 43driver supports ATAPI (also called IDE) devices such as CD-ROMs, ZIP 44drives, LS-120 floppy drives, and tape drives. 45All ATAPI devices talk a subset of the SCSI protocol. 46.Pp 47The 48.Nm 49driver acts like a SCSI adapter. 50Thus, the ATAPI devices connected to the system will appear as SCSI devices. 51ATAPI CD-ROMs will appear as 52.Xr cd 4 53devices, ATAPI tape drives as 54.Xr st 4 55devices, and ATAPI floppies as 56.Xr sd 4 57devices. 58.Pp 59For performance reasons, one should avoid putting an ATAPI device and 60a hard disk on the same cable. 61The driver does not support bus release and, even if it did, many ATAPI 62devices do not support it. 63There is only one command outstanding on a cable at a time. 64For example, if a hard disk and a CD drive are placed on the same cable, 65the hard disk requests may get queued behind slower CD operations. 66.Pp 67The 68.Cm flags 69are used only with controllers that support DMA operations and 70mode settings (like some 71.Xr pciide 4 72controllers). 73The lowest order (rightmost) nibble of the 74.Cm flags 75define the PIO mode to use. The next four bits indicate the DMA mode and the 76third nibble the UltraDMA mode. 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