A Peripheral Interface Adapter (PIA) is a peripheral integrated circuit providing parallel I/O interfacing for microprocessor systems.
PIA pin configuration
┌─────⊔︀─────┐
Vss ┤ 1 40├ CA1
PA0 ┤ 2 39├ CA2
PA1 ┤ 3 38├ !IRQA
PA2 ┤ 4 37├ !IRQB
PA3 ┤ 5 36├ RS0
PA4 ┤ 6 35├ RS1
PA5 ┤ 7 34├ !RES
PA6 ┤ 8 33├ D0
PA7 ┤ 9 32├ D1
PB0 ┤10 31├ D2
PB1 ┤11 30├ D3
PB2 ┤12 29├ D4
PB3 ┤13 28├ D5
PB4 ┤14 27├ D6
PB5 ┤15 26├ D7
PB6 ┤16 25├ E
PB7 ┤17 24├ CS1
CB1 ┤18 23├ !CS2
CB2 ┤19 22├ CS0
Vcc ┤20 21├ R/!W
└───────────┘