NAME
pcppi —
PC (ISA) control port driver
SYNOPSIS
pcppi* at acpi?
pcppi* at isa?
isabeep* at pcppi? (alpha only)
sysbeep* at pcppi? (i386 only)
spkr0 at pcppi?
midi* at pcppi?
DESCRIPTION
Thepcppi driver handles resource allocation and device
attachment for the ports related to the ISA speaker in the traditional PC/AT
“design”. These are the “system control port”
(which was implemented by the 8255 “PPI” in the XT, hence the
name of this driver) at IO address 0x61.
When associated with an
attimer(4) device, it is possible to change the pitch of the sounds
emitted through pcppi.
The pcppi driver provides its child
devices with the ability to output simple tones through the PC speaker. The
speaker(4) and
midi(4) devices use this to synthesize sounds. The
isabeep(4) and
sysbeep(4) devices are helpers which the
pckbd(4) driver uses as a substitute for a “keyboard
beep”, because the PC keyboard hardware doesn't provide this.