expansion port -> /IRQ pin
VIC <- lightpen trigger
VIC <- Sprite to Sprite Collision
VIC <- Sprite to Background Collision
VIC <- Raster Compare Match
CIA1 <- Timer A Interrupt
CIA1 <- Timer B Interrupt
CIA1 <- TOD alarm Interrupt
CIA1 <- serial port interrupt
CIA1 <- flag <- cassette read
CIA1 <- flag <- serial bus SRQ

NMI (!!!!):
expansion port <-- /NMI
memory controller <- trigger/capacitor <- keyboard restore-key
CIA2 <- Timer A Interrupt
CIA2 <- Timer B Interrupt
CIA2 <- TOD alarm Interrupt
CIA2 <- serial port interrupt
CIA2 <- flag <- user port <- custom
CIA2 <- flag <- user port <- rs232 adapter
CIA2 <- flag <- user port <- centronics printer adapter