Date: Wed, 3 Nov 1999 10:21:17 +0200 (IST)
From: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
X-Sender: eliz AT is
To: Rob Kramer <robk AT cyberway DOT com DOT sg>
cc: djgpp AT delorie DOT com
Subject: Re: DMA despair.
In-Reply-To: <199911030812.QAA28439@westgate.cyberway.com.sg>
Message-ID: <Pine.SUN.3.91.991103101622.29867A-100000@is>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
Reply-To: djgpp AT delorie DOT com
X-Mailing-List: djgpp AT delorie DOT com
X-Unsubscribes-To: listserv AT delorie DOT com
Precedence: bulk


On Wed, 3 Nov 1999, Rob Kramer wrote:

> It's IRQ 10 decimal..

IRQ 10 requires to set up both the Master and the Slave Interrupt 
Controllers, and send the EOI command to both of them.  Make sure your 
code does this.

> This seems like a good idea, but I couldn't find any info on how to read 
> those registers. I found some docs that show that I first have to set 2 bits, so 
> that the next read will give me the IRR or the ISR. But how do I chose which 
> of the Command Words will be written?

You read these registers of the slave controller by reading port 0Ah.  You
specify what register to read by sending a command (writing) to port 0Ah
before reading it.  A command value of 0Ah selects the IRR, the Interrupt
Request Register, while the value 0Bh selects the ISR, the Interrupt
In-Service Register.