Date   : Wed, 20 Jul 1994 20:37:53
From   : JAMES WARD <J.Ward@...>
Subject: Re: Calculating branch addresses

Stephen Quan wrote:

> It might crash is when the PC falls of the end of the array, but
> I assume in real life this would never happen.  The only time when the
> PC ever gets this high is when the BBC itself resets and calls the code
> stored at &FFFE, but even then that is a jump instruction which will
> take the PC back to a reasonable value.  It will take someone with a
> deliberate intention to crash the emulator in order to crash it
> successfully.

Isn't there a bug in the 6502, in that it doesn't carry when it adds
up indirect address and thus pulls the indices from the wrong pair of
memory locations?  I seem to remember reading something to this
effect in the Advanced User Guide.
I can't remember the details off the top of my head, but if this is
true then it's worth being aware of.  I am not sure whether 65C02
etc. duplicate this bug/feature or not.
  James.
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( E-Mail:  j.ward@...                                        )
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