I have a really basic question. I have to design an 65C02-based personal computer for a school project. I have to draw my own footprint for the 65C02. My question is what type of pin is the IRQB (Interrupt) pin? I know what the purpose of the pin is. I have no idea if it is Input or Output... or Bidirectional. The datasheets have no mentions on what each pin is as far as type.
The interrupt pin is an input.
The W65C02 data sheet does explain it (p. 9):
3.4 Interrupt Request (IRQB)
The Interrupt Request (IRQB) input signal is used to request that an interrupt sequence be initiated. The program counter (PC) and Processor Status Register (P) are pushed onto the stack and the IRQB disable (I) flag is set to a "1" disabling further interrupts before jumping to the interrupt handler. These values are used to return the processor to its original state prior to the IRQB interrupt. The IRQB low level should be held until the interrupt handler clears the interrupt request source. When Return from Interrupt (RTI) is executed the (I) flag is restored and a new interrupt can be handled. If the (I) flag is cleared in an interrupt handler, nested interrupts can occur. The Wait-for- Interrupt (WAI) instruction may be used to reduce power and synchronize with, as an example timer interrupt requests.
So it not only tells you that this is an input signal, it also explains how long it should be held at low level.
The General Timing Diagram (Figure 6-3, p. 26) has some more timing information for IRQB.
An interrupt pin of a CPU will always be an Input.
After all, it's whole purpose is to tell the CPU about an interrupt pending. Wouldn't work if it's an output, would it?