Re: Hardware emulation of 6509 using 6502?

From: Segher Boessenkool <*segher_at_kernel.crashing.org*> Date: Sun, 25 Feb 2018 13:06:20 -0600 Message-ID: <20180225190620.GO21977@gate.crashing.org> · segher_at_kernel.crashing.org

On Sun, Feb 25, 2018 at 06:39:52PM +0100, Michał Pleban wrote:
> Michał Pleban wrote:
> 
> > However, it is possible that these locations ARE corrupted but in the
> > current execution bank; since the ROM code always runs from bank $F,
> > corrupting values $F0000 and $F0001 is not a big deal.
> 
> It also brings the reverse problem - if a location $0000 or $0001 os
> being read by the a LDA (xx),Y operation, will it read the CPU register
> or underlying RAM?

On the 6510 it is the CPU register.  I'd assume 6509 is implemented
similarly (but there are no die pictures to compare AFAIK).

Segher

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