Description

This item is from the PC Hardware FAQ, by Willie Lim and Ralph Valentino with numerous contributions by others. (v1.25).

2.49 Where do all the IRQ's and DMA Channels go?

[From: wlim@lehman.com (Willie Lim)]

[From: r.j.mersel@is.twi.tudelft.nl (Rob Mersel)]

(Note that DRQ is the DMA Channel)

Default IRQ/DRQ settings AT systems:

IRQ   IO BASE   DRQ   Card or Device
      ADDRESS
      (HEX)
===   =======   ===   ================
 *       *       0    unassigned (? bit DMA)
 *       *       1    unassigned (8 bit DMA)
 *       *       3    unassigned (8 bit DMA)
 *       *       5    unassigned (16 bit DMA)
 *       *       6    unassigned (16 bit DMA)
 *       *       7    unassigned (16 bit DMA)
 0       *       *    timer (reserved)
 1       *       *    keyboard (reserved)
 2       *       *    interrupt 8-15 (cascade) (see Q 2.40)
 3    2E8-2EF    *    COM4:
 3    2F8-2FF    *    COM2:
 4    3E8-3EF    *    COM3:
 4    3F8-3FF    *    COM1:
 5    278-27F    *    LPT2:
 6    3F0-3F7    2    Floppy drive controller
 7    378-37F    *    LPT1: (PRN:)
 8       *       *    real-time clock (reserved)
 9       *       *    unassigned (see Q 2.40)
10       *       *    unassigned
11       *       *    unassigned
12       *       *    unassigned
13       *       *    math co-processor
14    1F0-1F7    *    Hard drive controller (drive 0)
14    3F6-3F7    *    Hard drive controller (drive 1)
15    170-177    *    Secondary hard drive controller (drive 2)
15    376-377    *    Secondary hard drive controller (drive 3)

Adapter card IRQ/DRQ settings:

IRQ   IO BASE   DRQ   Card or Device
      ADDRESS
      (HEX)
===   =======   ===   ================
 *    200-207    *    Game port
 2      330      *    MPU-401 Emulation (PAS 16)
 3      300      *    3Com Etherlink II, II/TP, II/16, II/16TP, 16/16TP
 3      300      *    Novell NE2000
 3      300      *    SMC/Western Digital 8003EP, 8013EWC, 8013WB
 5      368      *    Ungermann-Bass Ethernet NIUpc (long), NIUpc/EOTP (short)
 5      ???      *    DEC etherWORKS LC, Turbo, Turbo/TP
 5      220      1    Sound Blaster Emulation (PAS 16)
 5    220-22F    1    Sound Blaster 2.0 (default)
 *    338-339    *    Sound Blaster 2.0 FM music chip
 5      A20      5    Proteon P1390
 7       *       3    Pro Audio Spectrum 16 (PAS 16)
 9      300      5    Boca Ethernet BEN100, BEN102, BEN300

Default IRQ/DRQ settings XT systems:

IRQ   IO BASE   DRQ   Card or Device           
      ADDRESS
       (HEX)
===   =======   ===   ===============
 *       *       0    DRAM-refresh (used on motherboard only?)
 *       *       1    unassigned
 0       *       *    timer (reserved)
 1       *       *    keyboard (reserved)
 2       *       *    unassigned
 3    2E8-2EF    *    COM4:
 3    2F8-2FF    *    COM2:
 4    3E8-3EF    *    COM3:
 4    3F8-3FF    *    COM1:
 5       ?       3    Hard drive controller
 6    3F0-3F7    2    Floppy drive controller
 7    378-37F    *    LPT1: (PRN:)

 

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• prev: 2.48 Can I use IRQ2 or is it special?
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• next: 3.02 How can I tell if I have MFM/RLL/ESDI/IDE/SCSI?

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