HELP! More interrupt questions

[dg04@ns1.cc.lehigh.edu (DAVID GRUMBINE)]

Thanks for your replies on interrupts.  But I still got problems!

I got a card that generates interrupts.  No problem.
I wrote an interrupt processor that deals with the above interrupts.  No
problem.  In DOS 3.3 on an Apple ][+ with 48k.  Only other card is the
drive interface.

Problem:  Applesoft seems to do some funny things once in a while when the
interrupt processor is working.  If I take it out (but the interrupts are
still being generated) it works fine.

The interrupt processor saves the values of all the registers upon entry.
If the interrupt is deemed not caused by the card (and the hardware end of this
system works also), it jumps to the old interrupt handler (address $FF65).
This handler obviously works without interference to Applesoft, although I
can't figure out what it's supposed to do.  Looks like decoding monitor
commands or something.

Anyway, my processor saves the registers on entry, and if it WAS caused by the
card, it branches to the rest of the routine, where upon it increments some
memory locations, restores the registers, and does an RTI.  All of the
program and locations used by it are in page $03, so it doesn't interfere with
the zero page at all (and ends well before all the vectors around $3F0).
Supposedly, the 6502 saves the processor status before jumping to the interrupt
routine, and RTI restores this at the end, so that shouldn't be the problem.

I wish I could post the code, but I haven't gotten file transfer between my
IBM and the Apple to work yet.  I think the IBM serial port needs some coaxing
for it to work on 3 lines (expects a modem or something... any ideas on this?)

So, any help would be appreciated ALOT.  In case my .sig file isn't there,
my e-mail address is dg04@Lehigh.EDU.  Thanks.

-dave
-- 

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The oppinions expressed above may or may not be my own.  But I'm not telling.

Physics is fun! ....  Honest.
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Dave Grumbine, Jr.       dg04@Lehigh.EDU