Re: 6502 stack register at reset

From: didier derny <*didier_at_aida.org*> Date: Sat, 25 Nov 2017 22:11:02 +0100 Message-ID: <26843ceb-2284-1c78-992f-d6f65e13d77e@aida.org> · didier_at_aida.org

frankly I have no idea, but I observed the problem...

the same code was working on SYM1/ CBM 8032

and randomly crashing on replica 1

it stopped crashing on replica 1 when I initialized the stack myself...

On 25/11/2017 22:03, Spiro Trikaliotis wrote:
> Hello,
>
> * On Sat, Nov 25, 2017 at 08:50:21PM +0100 didier derny wrote:
>> Is there any 6502 starting with an initialized stack register at reset ?
>>
>> a few month ago I was struggling with a strange bug...
>>
>> the program was crashing or working randomly
>>
>> I discovered that the machine had a stack register never initialized
> But: Why is this a problem? I would expect the stack pointer just to
> wrap around.
>
> That is, if you have RAM at $0100-$01FF and you do not use that area for
> anything else, why should the CPU crash at all as long as you do not
> push more than 256 byte on it?
>
> Can anyone enlighten me?
>
> Regards,
> Spiro.
>

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