IRQ mess "made by WINDOWS"

[Mahimahi]

Intend to build my first homegrown computer, but getting a bit scared!

Can anyone please give me an explanation about some of the IRQ’s which I don’t understand in the following table (copied from my existing computer).
No problem for the obvious device IRQ’s, only 02, 03, 05, 05bis, 10bis, 11bis, 12bis, 14, 14bis, 15 and 15bis are all but clear to me.
- Do I really need all this, or are the doubles only a slovenliness of the Windows householding?
- How come 03 is not taken?
00 - System timer
01 - Keyboard
02 - Programmable interrupt controller
03 - ??????
04 - Com 1
05 – Intel 82371AB/EB universal host controller for PCI to USB
05 – IRQ holder for PCI steering
06 – Standard diskette station controller
07 – ECP printer port controller
08 – System CMOS/Real-time clock
09 – Soundblaster 16 or AWE 32 or compatible
10 – Conexant PCI modem emulator
10 - IRQ holder for PCI steering
11 – Diamond Viper 550
11 - IRQ holder for PCI steering
12 – Adaptec AHA-294X/AIC-78XX PCI SCSI controller
12 - IRQ holder for PCI steering
13 – numeric processor
14 – Intel 82371AB/EB PCI Busmaster IDE-controller
14 – Primary IDE controller (double fifo)
15 - Intel 82371AB/EB PCI Busmaster IDE-controller
15 – Secondary IDE controller (double fifo)

Configuration of existing system:

ASUS P2L97 mobo
Diamond VIPER550
VOODOO II
64 Mb ram
SCSI controller
JAS 2Gb SCSI
Scanner Agfa SCSI
HD Seagate IDE 10Gb
Modem Conexant (Rockwell) 56K intern
Floppy drive
CDRom Mtpr 40X

System to build:

Midi tower in Aluminium 400Watt power supply and 3 ventilators
Mobo ASUS A7M266
AMD Thunderbird Athlon 1.2 GHz with compatible heatsink and fan.
256Mb PC2100 DDR SDRAM
ASUS V7700Ultra Graphics card
Sound blaster vallue
CDROM 40X MTRP
CD-RW Plextor “Plexwritor” 12X10X32
Two HD drives IBM 45 giga ata100
Jaz drive 2GB (recup. Old pc + existent SCSI card)
PCI Controller card for external cable modem (normal use of the internet and games)

Can anyone clear this up a bit for me please?
Thanks in advance,
Roger

 

[Guest]

Looks pretty good to me...

Nothing major is being shared.

Learning has begun.

 

[Crashman]

IRQ 3 was originally taken by Com 2 bach in the days before ps/2 style mice. It has often been used for a Com 4 on a jumper configured modem. I use mine for my SCSI card. If you ever have resorce conflicts in Windows, you can usually have BIOS set them for you.

 

[girish]

that seems quite a lot. IRQ 3 is supposed to be used by COM2, but it isnt, might have been disabled in the BIOS. you dont need a serial port if you have a PS/2 mouse, so you can disable it and get an extra IRQ.

girish

 

[Mahimahi]

Thanks guys, but what about the doubles like the
"IRQ holder for PCI steering" I have it 4 times. Is this normal?

 

[Guest]

I see it all the time (i.e. "IRQ holder for PCI steering") and the stuff works.

You should look at your system as it's booting to see what irq assignments you have. You may find that irq3 is taken up by the acpi controller.

 

[jg38141]

The irq pci steering etc. is good and important. It's what allows your motherboard to talk to the device installed. For example, the hardware may take up an irq, but without the pci stering the motherboard's northbridge can't use the hardware. So basically each hardware irq is shared between the hardware its self and the motherboard that uses it. I hope that clears things up. Oh yeah- don't remove those IRQ holder for PCI steering things.
If you're wondering where it originally comes from- I'm pretty sure they show up when you install the VIA 4in1 drivers which inables all the abilities of the north bridge including udma capabilities.

"Are you saying that I can dodge bullets?"

 

[Mahimahi]

Lots of thanks for the help guys

 

[silverpig]

Might be a little off topic here, but I'm wondering why you are going for a CDROM and not a DVD in the new system. You seem to have everything else...