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.Dd $Mdocdate: November 2 2017 $
.Dt IOASIC 4 alpha
.Os
.Sh NAME
.Nm ioasic
.Nd
baseboard IO control ASIC for DEC TURBOchannel systems
.Sh SYNOPSIS
.Cd "ioasic0 at tc? slot ? offset ?"
.Sh DESCRIPTION
The
.Nm
driver provides support for the DEC proprietary IOCTL ASIC found on
DEC 3000 TURBOchannel machines.
.Pp
The
.Nm
provides hardware DMA channels and interrupt support for several
baseboard devices, including one
.Xr asc 4
SCSI device with a scatter/gather DMA channel, an mc146818-compatible
.Nm mcclock ,
an Am7930 audio device
.Xr bba 4 ,
two
.Xr zs 4
dual-port serial devices, and an AMD 7990 LANCE
.Xr le 4
Ethernet interface.
.Pp
The
.Nm
is also used for the audio/ISDN hardware on
audio-equipped TURBOchannel Alphas,
where the
.Nm
hardware provides a scatter-gather DMA channel between the 16-bit
device and the 32-bit
.Nm tc
DMA address space.
.Pp
Support for scatter-gather DMA eliminates the need for additional copying.
.Sh SEE ALSO
.Xr asc 4 ,
.Xr bba 4 ,
.Xr intro 4 ,
.Xr le 4 ,
.Xr zs 4
.Sh HISTORY
The
.Nm
driver
first appeared in
.Nx 1.1 ,
derived from DECstation boot-time configuration code in
.Bx 4.4  .