[comp.sys.atari.st.tech] Interrupt question

galileo@crash.cts.com (Steve Klug) (09/19/90)

	I am trying to write a program which automatically does something
upon getting a carrier on the modem.  I'd like to write an interrupt routine,
preferably in GCC to handle this.  What I need to know is how to enable the
carrier detect interrupt.  I assumed (a horrible thing to do) that you 
simply had to place the proper address in the interrupt vector (0x104 ???)
while in supervisor mode and that it would fly.  Needless to say, it didn't
work.
Summary:	I need some general guidelines on how to work with Atari ST
interrupts from C, or from assembly if I have to.  More specifically, I need
to know how to use the carrier detect interrupt if there is anything special
about that particular interrupt.

			galileo@crash.uucp

hyc@math.lsa.umich.edu (Howard Chu) (09/20/90)

In article <4501@crash.cts.com> galileo@crash.cts.com (Steve Klug) writes:
>	I am trying to write a program which automatically does something
>upon getting a carrier on the modem.  I'd like to write an interrupt routine,
>preferably in GCC to handle this.  What I need to know is how to enable the
>carrier detect interrupt.  I assumed (a horrible thing to do) that you 
>simply had to place the proper address in the interrupt vector (0x104 ???)
>while in supervisor mode and that it would fly.  Needless to say, it didn't
>work.

I'm not at home so I can't check into this too thoroughly, but you're probably
not enabling the interrupt. It's disabled by default. Check the docs for the
Jenabint Xbios call, or read your docs on the MFP68901 to see which bits to
toggle...
--
  -- Howard Chu @ University of Michigan
  one million data bits stored on a chip, one million bits per chip
	if one of those data bits happens to flip,
		one million data bits stored on the chip...