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Re: [Hook out HW interrupt IRQ14 with Watcom C+DOS/32a in DOS ]

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"cg_chas" <cg_chas@hotmail.com> wrote in message
news:c1c2189dt85g18udo3h46maap0pqnlq2kq@4ax.com...
> On Wed, 25 Jul 2012 21:42:19 -0700 (PDT), liaoo <jimmyliaoo@gmail.com>
wrote:

> Since your motherboard _does_ have an I/O APIC, you must see what has to
> be done to disable it, otherwise, I am guessing you will not be able to
> use the standard PIC(s) the way you want to.

He can use the 8259's until I/O APIC is enabled.  I use them on machines
with I/O APICs without ever using the I/O APICs.  The 8259's are either
present as hardware or emulated via BIOS or somesuch...

In an OS project of mine, I use the standard BIOS IRQ setup for my PICs.
0x08 for PIC1 and 0x70 for PIC2.  Although, I do set them via ICW2
just to make sure they are the values I expect.

Most people say you need to remap the PICs since they are shared between
interrupts and IRQ's.  That's not actually true.  You can determine what
triggered a specific interrupt afterwards.  It just takes more work:

In an interrupt, you can check the instruction stream (IP saved on stack) to
see if the last instruction was an INT instruction (0xCD).  If so, the
interrupt is a software interrupt, or it could be a fault.  You can then
check to see if the software interrupt number called matches the interrupt
number you're in.  If not, it's a fault, instead of a software interrupt.
If the interrupt number is a possible IRQ interrupt, you can read the low or
high PIC's ISR register to see if it was an IRQ.  If so, the interrupt is an
IRQ.  The routine I use to separate these is more complicated than that, but
that's the basic outline.


Rod Pemberton

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Thread

[Hook out HW interrupt IRQ14 with Watcom C+DOS/32a in DOS ] liaoo <jimmyliaoo@gmail.com> - 2012-07-25 08:50 -0700
  Re: [Hook out HW interrupt IRQ14 with Watcom C+DOS/32a in DOS ] cg_chas <cg_chas@hotmail.com> - 2012-07-25 22:41 -0400
    Re: [Hook out HW interrupt IRQ14 with Watcom C+DOS/32a in DOS ] liaoo <jimmyliaoo@gmail.com> - 2012-07-25 20:06 -0700
      Re: [Hook out HW interrupt IRQ14 with Watcom C+DOS/32a in DOS ] cg_chas <cg_chas@hotmail.com> - 2012-07-26 00:06 -0400
        Re: [Hook out HW interrupt IRQ14 with Watcom C+DOS/32a in DOS ] liaoo <jimmyliaoo@gmail.com> - 2012-07-25 21:42 -0700
          Re: [Hook out HW interrupt IRQ14 with Watcom C+DOS/32a in DOS ] cg_chas <cg_chas@hotmail.com> - 2012-07-26 09:07 -0400
            Re: [Hook out HW interrupt IRQ14 with Watcom C+DOS/32a in DOS ] liaoo <jimmyliaoo@gmail.com> - 2012-07-26 08:10 -0700
            Re: [Hook out HW interrupt IRQ14 with Watcom C+DOS/32a in DOS ] "Rod Pemberton" <do_not_have@notemailnot.cmm> - 2012-07-27 16:13 -0400
              Re: [Hook out HW interrupt IRQ14 with Watcom C+DOS/32a in DOS ] liaoo <jimmyliaoo@gmail.com> - 2012-07-27 23:04 -0700
                Re: [Hook out HW interrupt IRQ14 with Watcom C+DOS/32a in DOS ] liaoo <jimmyliaoo@gmail.com> - 2012-07-27 23:38 -0700
  Re: [Hook out HW interrupt IRQ14 with Watcom C+DOS/32a in DOS ] cg_chas <cg_chas@hotmail.com> - 2012-07-25 22:51 -0400
  Re: [Hook out HW interrupt IRQ14 with Watcom C+DOS/32a in DOS ] JJ <jaejunks_at@_googlemail_dot._com> - 2012-07-26 14:05 +0000
    Re: [Hook out HW interrupt IRQ14 with Watcom C+DOS/32a in DOS ] liaoo <jimmyliaoo@gmail.com> - 2012-07-26 07:41 -0700
  Re: [Hook out HW interrupt IRQ14 with Watcom C+DOS/32a in DOS ] "Rod Pemberton" <do_not_have@notemailnot.cmm> - 2012-07-27 16:13 -0400
    Re: [Hook out HW interrupt IRQ14 with Watcom C+DOS/32a in DOS ] liaoo <jimmyliaoo@gmail.com> - 2012-07-27 22:57 -0700
      Re: [Hook out HW interrupt IRQ14 with Watcom C+DOS/32a in DOS ] "Rod Pemberton" <do_not_have@notemailnot.cmm> - 2012-07-28 05:06 -0400
        Re: [Hook out HW interrupt IRQ14 with Watcom C+DOS/32a in DOS ] liaoo <jimmyliaoo@gmail.com> - 2012-07-28 05:52 -0700
        Re: [Hook out HW interrupt IRQ14 with Watcom C+DOS/32a in DOS ] liaoo <jimmyliaoo@gmail.com> - 2012-08-14 20:15 -0700

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