It is an electronics term... So far as I know, such as in; https://en.wikipedia.org/wiki/Pull-up_resistor

I would have explained it, but I think the article is probably better... Well... OK, I'm being lazy.

I guess they must be using pull-up/down resistors somewhere on the board. Or else, are implementing something to ensure a certain logic level is reached on the interrupt pins. Either way, the jumper settings are a bit tedious on this board.

First, what is an IRQ? In a nutshell, a device on your computer called the interrupt controller listens to the appropriate pin on the card for the voltage level on that pin to be disturbed from normal. If it picks up a signal, it alerts the CPU. On PCI devices, the interrupt pin will naturally be at high voltage and be pulled low by a transistor on the card to signal an interrupt. A resistor safely connects the pin to positive signal voltage to pull the pin up to a high signal when not active. This is also preventing shorts.

ISA devices are naturally opposite, so you need a pull down resistor.

From what I understand, you should pull down the IRQ used by a PCI device - say you're using a PCI video card on IRQ 10 - then IRQ 10 should be jumpered to pull down. Not 100% sure but will experiment myself.

PCI is active low, so the resistor will be pulling high, and the mosfet will pull low when the irq is triggered.

Thanks all... So..... I just follow the manual and do what it say's then. 🤣

Yup.

Not jumping down the rabbit hole?