PC (ISA) control and timer port driver
pcppi* at isa?
spkr0 at pcppi?
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 I/O address 0x61 and the first 8253 timer at
driver provides its child devices
with the ability to output simple tones through the PC speaker. The
uses this to synthesize sounds. It also provides helper functions to the
driver as a
substitute for a “keyboard beep”, because the PC keyboard
hardware doesn't provide this.