Re: A86: Questions on Port 3, calc on, off, APD, etc


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Re: A86: Questions on Port 3, calc on, off, APD, etc




>No, the [ON] interrupt is an NMI (non-maskable interrupt).  It
>cannot be shut off.  It is written on the circuit board.  In fact,
>because of this, you will never have to pull all 5 batteries
>unless sqrtON (or whatever the user [ON] interrupt handler is)
>is corrupted.

It is not an NMI. Someone please back me up at this. If it was, the shutdown
routines would have a di and a halt statement. The NMI would get through the
di. Where is it written on the circuit board? You can STILL hard lock the
calculator, and there is NO sqrtON handler.

You dont believe me? Try this

di
halt
ret

Now DI doesnt affect an NMI so if the ON key was really an NMI then this
wouldnt lock the calc. When the ON key was pressed, it would call the
interrupt, come back, and return to the system. If this code doesnt crash,
tell me, but then I will really really be suprised

I disassembled the ROM, the interrupt handler is fixed in the code, it makes
a jump to the ON key interrupt handler routine. I did over 5 hours of
disassebling and came to the conclusion there are no NMI's.. I have been
reading some of the messages about interrupts by Jimmy Mardell and he also
says "The TI-8x doesn't have any NMI's" and someone (maybe him) also says
they haven't even seen a computer with an NMI

Later,
    Matt


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