Date: Wed, 18 Aug 1999 15:29:52 +0300 (IDT)
From: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
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To: Martin Peach <martin AT loplop DOT com>
cc: djgpp AT delorie DOT com
Subject: Re: hardware ints
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On Sun, 15 Aug 1999, Martin Peach wrote:

> Although I enabled the receive character interrupt in the IER register of
> the UART and set the PIC interrupt mask, I am not sure if the UART is
> generating interrupts to the 8259 PIC. Is there a way to check for this?

One way of doing this would be to read the Interrupt Request Register and 
Interrupt In-Service Register of the PIC, and check whether the bit 
corresponding to IRQ3 is set.

> Is it OK to use a protected mode handler for the COM ports?

Yes.

> Is something else getting to my interrupts before I get there?

No, hardware interrupts are always sent to the protected-mode handler 
first.