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Interrupt levels all gone; Where? Sharing possible?

Posted on 1998-09-27
Medium Priority
Last Modified: 2013-12-16
Interrupt levels all gone; Where? Sharing possible?

On my P133 Win95 PC, I added a new card, and am now in interrupt level trouble.

Interestingly; when I added a SCSI card it took level 11, which had been used by a sound card. The sound card then (transparently, dnamically) tried to adjust and move to interrupt level 10; but 10 was full with my Ethernet card, so the sound card reported a conflict, and stopped working.
I had actually already physically removed the EN card anyway (replaced it in my limited EISA slots with the SCSI card). So, when I removed the device logically, bingo, the sound card immediatley found interrupt 10, took it, and started working.

Now, I need networking back.
I bought a new PCI card; but wonder how to work the interrupts. All of my interrupts are full:

       ******************** IRQ SUMMARY ********************
       IRQ Usage Summary:
         00 - System timer
         01 - Standard 101/102-Key or Microsoft Natural Keyboard
         02 - Programmable interrupt controller
         03 - Communications Port (COM2)
         04 - Communications Port (COM1)
         05 - Reveal WAVExtreme 32 FM/SB Emulation
         06 - Standard Floppy Disk Controller
         07 - ECP Printer Port (LPT1)
         08 - System CMOS/real time clock
         09 - Reveal WAVExtreme 32 MPU-401 Emulation
         10 - Reveal WAVExtreme 32 Synth/Codec
         11 - Symbios Logic 53C416 Plug and Play SCSI Adapter
         12 - Logitech PS/2 Port Mouse
         13 - Numeric data processor
         14 - Standard Dual PCI IDE Controller
         14 - Primary IDE controller (single fifo)
         15 - Standard IDE/ESDI Hard Disk Controller

1) can devices share interrupt levels? Some machine architectures allow this, a vector from the original hardware interrupt address. On my NT, it does report both levels, and vector for each interrupt device.
  I.e. Can I somehow share the network card (NIC) with some other device? The previous experience shows that it didn't share with the sound card.

2) I notice that on my NT, I have many fewer interrupts:
IRQ and Port Report
      Devices                   Vector   Level  Affinity
      i8042prt                         1      1    0xffffffff
      i8042prt                       12    12    0xffffffff
      Serial                             4      4    0x00000000
      Serial                             3      3    0x00000000
      El90x                           11    11    0x00000000
      Floppy                           6      6    0x00000000
      sb16snd                       53      5    0x00000001
      atapi                              0    14    0x00000000
      atapi                              0    15    0x00000000

Why so many less? I also note that the Parport (LPT1) doesn't take any interrupt?
  (The NT is a newer motherboard...)

3) I particularly notice that my sound card on the W95 machine (Reveal, WaveExtreme 32) takes two additional interrupts (9,11) that the sound card on the NT (Creative SB32-PNP) doesn't (only uses Int5); Why? dos this mean that if I were to switch sound cards, I would recover two interrupts? And then perhaps use one for my (Linksys Combo PCI -2 : LNEPCI2) card?


Greg Guthrie
 (Please also reply via Email: guthrie@Mum.edu)
Question by:guthrie
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Accepted Solution

bashley earned 200 total points
ID: 1758501
You have a few options for recovering interrupts:
1. If you're not using both of your serial ports, disable what you aren't using and recover interrupt 3 or 4.
2. If you don't have more than 2 IDE devices, configure your one or two devices only on the primary port; Disable the secondary port and recover interrupt 15.
3. Consider using a serial mouse so you could disable the mouse port and recover interrupt 12.
4. Windows will run the LPT ports without an interrupt or will let you assign the LPT interrupt (number 7) without declaring a conflict.  I mention this last since it sometimes takes some trials to get it working.
About the sound card taking 2 interrupts: it probably has a tertiary IDE port which can be disabled.
NT does not require fewer interrupts; It just does not tell you about some of them.

Author Comment

ID: 1758502

1) I use both serial ports;
  -- I may be able to dump one; I'll check.(I use it for PPP network conection, could replace once I get teh HIC connected).

2) I use all the IDE ports. (2 disks, CDrom, and CD-RW)

3) Serial mouse is an interesting idea; but if I free a serial port, I suppose it would be just as good (?).

4) This sounds like the best bet. How do I do this?
  Just install the NIC and try to put it onto Int7 ?

-- I think it does have teh 3rd IDE, but it is disabled, and thus I think takes no interrupts;
       Class: Hard disk controllers
       Device: Secondary IDE controller (single fifo)
       No resources used.

       Class: Hard disk controllers
       Device: WAVExtreme 32
       No resources used.

The two extra that it does take are:
         09 - Reveal WAVExtreme 32 MPU-401 Emulation
         10 - Reveal WAVExtreme 32 Synth/Codec
       DMA Channel Usage Summary:
         05 - Reveal WAVExtreme 32 Synth/Codec
         06 - Reveal WAVExtreme 32 Synth/Codec

I wondered if there were somehow artifacts of it emulating a SBlaster, instead of really being one. I thought this since the NT (true SB) card has no corresponding device shown.


Expert Comment

ID: 1758503
Well, I know that a Creative Labs Soundblaster doesn't take 3 interrupts to work.  In the long run, you may be better off replacing your sound card, because your current one is a resource hog.  That's not to say that it isn't a good sound card, just that it takes a pretty big footprint in your system. Usually a SoundBlaster will take IRQ5, which would open up 9 and 10 for you.  I do have a question, however:  What IRQ is your video adapter on?  I don't see it listed.  It must be sharing with something.  

Expert Comment

ID: 1758504
Greg, I don't understand your Reveal WAVExtreme setup; My SB card uses one interrup for wave, midi, and midi wave-table synthesis.  Could your Reveal WAVExtreme have been installed twice?  Why it needs two interrupts and two dma channels is a good question for their tech support line...  If that's the way it's supposed to be I agree with nybdfool that I'd dump it.
I've shared or disabled the interrupt on lpt2 several times, but not lpt1.  I'm not sure why lpt1 is different unless it's because you have it setup as ECP.  ECP uses a dma channel which probably necessitates an IRQ line to control it.  Maybe it would be worth the sacrifice to drop back to "Standard" lpt1 which you probably have to do in your BIOS setup.  I believe one of the non-automatic configurations in device manager will spec an address without an interrupt when you aren't using ECP/EPP.


Expert Comment

ID: 1758505
IRQs can be shared on the PCI bus.
If the network card is Plug N Play, just install it and it will happily share an IRQ with another device.
Windows will install an IRQ steering resource to permit this.

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