Re: A86: interrupts

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Re: A86: interrupts


we're running this from the user int routine (_alt_interrupt_exec) which
means we have to pop back to the interrupt before executing reti. all
reti does is make sure good things happen if you have nested interrupts
(which i don't think could happen because i don't think the 86 has a
non-maskable interrupt)

Dux Gregis wrote:
> 
> Kirk Meyer wrote:
> >
> > i see no reason for pushing & poping - there's nothing to be saved if
> > you disassemble the int handler. if you're using the built-in int
> > support then you CAN skip the calc's interrupt - at the end, do the
> > following:
> 
> What does the rest of the interrupt do?  I can't tell what's going on
> those ports.
> 
> >
> > pop hl
> > exx
> > ex af,af'
> > reti
> 
> <reti> loads (sp) into pc.  This will crash since you already popped the
> program counter.  But, if you take out <pop hl> it will speed up the
> interrupt.  :-))
> 
> >
> > and you should go back to where the interrupt was called from. in this
> > way the slow-down "feature" of the 86 could be avoided during games.
> > such a feature would be useful in ase or rascall (hint hint :)
> >
> > Dux Gregis wrote:
> > >
> > > I have two questions:
> > >
> > > Will the disable interrupt instruction disable the interrupt in
> > > interrupt mode 2?
> > > And, if instead of pushing the registers in an interrupt routine you did
> > > <pop hl>, would you have the program counter in hl from where the
> > > routine was called?  I don't think this would be possible using the
> > > regular interrupt because you would destroy the registers, but maybe
> > > using interrupt mode 2?
> >
> > --
> >
> > =====================================
> > =                                   =
> > =   Kirk Meyer (mailto:_@ibm.net)   =
> > = http://www.bigfoot.com/~kirkmeyer =
> > =                                   =
> > =   "Set your affection on things   =
> > =    above, not on things on the    =
> > =      earth."  Colossians 3:2      =
> > =                                   =
> > =====================================

-- 

=====================================
=                                   =
=   Kirk Meyer (mailto:_@ibm.net)   =
= http://www.bigfoot.com/~kirkmeyer =
=                                   =
=   "Set your affection on things   =
=    above, not on things on the    =
=      earth."  Colossians 3:2      =
=                                   =
=====================================
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