NAME
ioasic —
baseboard IO control ASIC for DEC
TURBOchannel systems
SYNOPSIS
ioasic0 at tc? slot ? offset ?
DESCRIPTION
The ioasic driver provides support for the
DEC proprietary IOCTL ASIC found on DEC 3000 TURBOchannel machines.
The ioasic provides hardware DMA channels
and interrupt support for several baseboard devices, including one
asc(4) SCSI device with a scatter/gather DMA channel, an
mc146818-compatible mcclock, an Am7930 audio device
bba(4), two zs(4) dual-port serial devices, and an AMD 7990 LANCE
le(4)
Ethernet interface.
The ioasic is also used for the audio/ISDN
hardware on audio-equipped TURBOchannel Alphas, where the
ioasic hardware provides a scatter-gather DMA
channel between the 16-bit device and the 32-bit tc
DMA address space.
Support for scatter-gather DMA eliminates the need for additional copying.
SEE ALSO
HISTORY
The ioasic driver first appeared in
NetBSD 1.1, derived from DECstation boot-time
configuration code in 4.4BSD.