Tutorial: Hardware Conflicts - IRQs and I/O Addresses
Results 1 to 7 of 7

Thread: Tutorial: Hardware Conflicts - IRQs and I/O Addresses

  1. #1
    Fastest Thing Alive s0nIc's Avatar
    Join Date
    Sep 2001
    Location
    Sydney
    Posts
    1,584

    Cool Tutorial: Hardware Conflicts - IRQs and I/O Addresses

    Each piece of hardware in a PC has an Interrupt Request (IRQ) and an Address. These are usually used by the CPU to identify each item and communicate with it when needed. Should two components be given thesame IRQ and thesame address, then a hardware conflict will occur. An error Message May be displayed and in some cases the computer may malfunction. The following Table shows a typical allocation of IRQs but this may vary in some detail from one computer to another


    IRQ-------- Used By

    0 -------------- System Timer
    1 -------------- Keyboard
    2 -------------- Interrupt Controller
    3 -------------- COM2 and COM4 (external modem usually on COM2)
    4 -------------- COM1 and COM3 (old models have mouse on COM1)
    5 -------------- LPT2 (may be sound card)
    6 -------------- Floppy Disk
    7 -------------- LPT1
    8 -------------- Real-Time Clock
    9 -------------- May be used for NIC (Network Interface Card)
    10 ------------ Usually CD drive controller
    11 ------------ Display Adapter
    12 ------------ May be used for NIC or tape drive
    13 ------------ Numeric data processor
    14 ------------ Fixed (hard) disk
    15 ------------ BIOS

    When installing add-on cards, you may be asked to set the IRQ and the address for that card. Alternatively, if you have Plug and Play (PnP) enabled (PCI motherboards), the computer will select and allocate the IRQ and the address automatically. If you motherboard does not have PnP, you can obtain software that can be installed to emulate PnP.

    Most computers have only one parallel port (LPT1) and although provision is made for LPT2 on IRQ5, in its absence other cards may use IRQ5. This is typically used when a sound card is installed. In other situations it may be used by a network interface card (NIC).

    Addresses are usually quoted in hexadecimal and can be confusing. Typically COM1 has an address of 3F8h. The h indicates hexadecimal and usually left off. When a computer is completing its Power-On-Self-Test (POST), it usually displays a table of hardware items just before handing over to the software tool. This table shows COM port and the parallel port address and the 3F8h is for COM1 and 2F8h is for COM2. The parallel port LPT1 is given the address 378h. If you have an internal modem set to COM4, it may have the address 2E8h. This will depend on the jumper settings or the PnP configuration.

    The serial ports COM2/COM4 share IRQs but have different addresses, so avoiding hardware conflicts.

  2. #2
    Fastest Thing Alive s0nIc's Avatar
    Join Date
    Sep 2001
    Location
    Sydney
    Posts
    1,584

    Cool

    hehe sorry d00ds.. i juz wanna keep dis on top so that the d00ds and d00detts that are sleeping 2night can read it 2morrow.. hehe hope i wont get flamed for this..

  3. #3
    Senior Member
    Join Date
    Dec 2001
    Posts
    291
    flamed even... he he

    naaaa.... just added to here

    9 is cascaded to 2 (they stress this for the A+ he he)
    From my experience Video, Nic, Scsi and Sound will gravitate around 7, 9, 5, and 11
    odd even

    If you've ever had problems with older linux versions and older pci video cards the 9 cascade is usually the reason...
    damn plug and play!!!

    ~THEJRC~
    ~THEJRC~
    I\'ll preach my pessimism right out loud to anyone that listens!
    I\'m not afraid to be alive.... I\'m afraid to be alone.

  4. #4
    Fastest Thing Alive s0nIc's Avatar
    Join Date
    Sep 2001
    Location
    Sydney
    Posts
    1,584

    Cool

    Hey jrc.. remember when you told me about that hardware with an IRQ of 90?.. were u serious or u were juz BS me?? lolz coz as far as i know there are only 15 IRQs

  5. #5
    Senior Member
    Join Date
    Dec 2001
    Posts
    291
    d00d..

    no BS really happened I couldnt figure it out... of course it didnt work but ever since then I wont touch a winmodem.

    I've also had restore cds pop up windows saying "some kind of error has occurred" with a little ok box that did nothing...

    yeah thats handy.... ****!


    ~THEJRC~
    ~THEJRC~
    I\'ll preach my pessimism right out loud to anyone that listens!
    I\'m not afraid to be alive.... I\'m afraid to be alone.

  6. #6
    Senior since the 3 dot era
    Join Date
    Nov 2001
    Posts
    1,542
    Originally posted by THEJRC

    From my experience Video, Nic, Scsi and Sound will gravitate around 7, 9, 5, and 11
    odd even
    Yep, especially for those old ISA (EISA) Cards:

    Midi drivers like MPU-401 use IRQ9 as default and many soundcards offer the choice between 5, 7, 9 but NIC's could be located at other IRQ's without a prob. for instance 10 and 12
    many SCSI adapters let you decide which IRQ to use.

    just some remarks

  7. #7
    Senior Member
    Join Date
    Jan 2002
    Posts
    108

    Post

    wow.. thats impressive. I've always wondered what those IRQ errors are. THANKS! This is one of the coolest tutorials i ever read!

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •