PCPPI(4) - Device Drivers Manual
PCPPI(4) - Device Drivers Manual # PCPPI(4) - Device Drivers Manual NAME # pcppi - PC (ISA) control and timer port driver SYNOPSIS # pcppi* at isa? spkr0 at pcppi? DESCRIPTION # The 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 0x40-0x43. ...