IRQ lines?

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4 total messages Started by Thomas Dwyer III Thu, 26 Jul 1990 00:41

#1675

Author: Thomas Dwyer III
Date: Thu, 26 Jul 1990 00:41

9 lines
874 bytes

Is it possible for a program to detect which IRQs are being used and
which are not?  It would be nice to have a program tell me which IRQs
are available when I install various cards in our machines here.

Thanks,
Thomas Dwyer III                            TOMIII   @ MTUS5.BITNET
Network Programmer                          DWYERIII @ MTUS5.BITNET
Computing Technology Services
Michigan Technological University

Re: IRQ lines?

#1680

Author: Kelly Keller
Date: Thu, 26 Jul 1990 12:51

15 lines
1113 bytes

TOMIII@MTUS5.BITNET (Thomas Dwyer III) writes:

>Is it possible for a program to detect which IRQs are being used and
>which are not?  It would be nice to have a program tell me which IRQs
>are available when I install various cards in our machines here.

This is possible. There are several programs available that help you to
manage your resources and IRQ's. One such program is Manifest (MFT) by 
Quarterdeck. I received it bundled with Quarterdeck's Memory Management
program QRAM, that enables you to manage your memory in extendend and
expanded fashions. MFT is a real help.
-- 
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   UUCP: iuvax!kelly 
   Internet: kelly@iuvax.cs.indiana.edu

Re: IRQ lines?

#1684

Author: Stephen Quigg
Date: Thu, 26 Jul 1990 22:24

8 lines
1121 bytes

In article <90206.194111TOMIII@MTUS5.BITNET> TOMIII@MTUS5.BITNET (Thomas Dwyer III) writes:
>Is it possible for a program to detect which IRQs are being used and
>which are not?  It would be nice to have a program tell me which IRQs
>are available when I install various cards in our machines here.
>
There's a program in the public domain called SYSID which is VERY useful
for sorting out your hardware. I,ve got v4.4a, which even comes with
sources (in C), and it should be easy to find on any good BB, archive, etc.

Re: IRQ lines?

#1691

Author: david nugent
Date: Fri, 27 Jul 1990 05:47

33 lines
1868 bytes

In <90206.194111TOMIII@MTUS5.BITNET> TOMIII@MTUS5.BITNET (Thomas Dwyer III) writes:

> Is it possible for a program to detect which IRQs are being used and
> which are not?  It would be nice to have a program tell me which IRQs
> are available when I install various cards in our machines here.

Quite easily.

You read the Programmable Interrupt Controller's interrpt enable mask;
any bit NOT set means that the corresponding IRQ is active.

So, for a PC machine with 8 IRQ levels, you would simply read it with an

	in  AL,20H

However, this doesn't mean that a particular IRQ is "available" for use
any another device.  It only means that the PIC has been programmed with
that IRQ active, which indicates that there is software in the system
servicing it.  There may well be add-on cards in your system configured
to use an IRQ, but they don't happen to be active at the time you read
the PIC.

Printer and communications ports are a good example of that.  They may
well be configured to run on a particular IRQ, but since MS-DOS doesn't
use them "interrupt driven" it doesn't activate the IRQ.  Placing another
card on your system which requires use of that IRQ may well cause a
clash.

-- 

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