What is the range of the legacy IRQs supplied by the motherboard?

Question

What is the range of the legacy IRQs supplied by the motherboard? Between what and what? One hard review for me.

1 to 15

0 to 14

0 to 15

1 to 8

Answer 1

Source Resolving Hardware Conflicts

Checking for conflicts

In order to unequivocally determine what IRQs, base addresses, and DMA channels are in use on non-PnP devices, you need to know the jumper/DIP settings of your cards.

This includes all of your ISA cards as well as any non-PnP devices on your motherboard. IRQ conflicts appear to be the biggest cause of conflicts. Base address and DMA conflicts aren't nearly as common (but if you have 2 or more of the same type of card in your system, for example, 2 MIDI/audio cards, the chances of base and DMA conflicts increase dramatically as many manufacturers of the same types of cards follow each others' "standards" for IRQ/address/DMA settings. For example, most MIDI cards use the Roland MPU-401 standard I/O address of 330).

Here's a list of what I've found to be the most common IRQ assignments. I think that it's pretty safe to assume these, but beyond the standard devices (ie, clocks, keyboard, serial + parallel ports, HD and floppy controllers, math chip), check all of your other devices:

IRQ #
0      System timer
1      Keyboard
2      Cascade for second interrupt chip
3      Serial (COM) port 2 (often a modem is attached to this)
4      Serial (COM) port 1 (usually a serial mouse is attached to this)
5      Parallel port 2 (not often used)
6      Floppy controller
7      Parallel port 1 (usually a printer is attached to this)
8      Realtime clock
9      free (but some video cards may use this for EGA emulation)
10     free
11     free
12     free
13     Math chip
14     HD (IDE) controller
15     Second IDE controller (usually a CD-ROM is attached to this. This second
       IDE controller may even be on your sound card, such as an SB card)

Typically, sound cards are set to use IRQ 5. This is often a good choice. Usually, IRQs 10, 11, and 12 are safe to use (assuming other ISA cards aren't using such). If the card has a MPU-401 compatible MIDI port, it usually uses I/O addresses 330 and 331 (hex). The MIDI port may also use another IRQ such as 9, separate from the IRQ used by the digital audio portion of the card.

*What is the range of the legacy IRQs supplied by the motherboard? Between what and what?

Between 0 and 15