Re: strange read with a 6502...

From: didier derny <didier_at_aida.org>
Date: Wed, 30 Mar 2016 10:22:47 +0200
Message-ID: <56FB8CD7.7020104@aida.org>
I know :( but I can observe the result, at odd addresses it works

at the beginning I thought the assembler was buggy
(before I reduced the function to 2 instructions)



On 30/03/2016 10:19, groepaz@gmx.net wrote:
> On Wednesday 30 March 2016, 10:06:21 didier derny <didier@aida.org> wrote:
>> I have a problem with a read with a 6502
>>
>> I read a data on a register (from a CH376S)
>>
>> I have the following code:
>>
>>                       *= 2000
>> readdata      LDA    CH376data
>>                        RTS
>>
>>
>> this code always get  the wrong value
>>
>>                       *= 2001
>> readdata     LDA    CH376data
>>                        RTS
>>
>>
>> now with this code I get the right value...
>>
>> I have a diffent result with a 6502 from:
>>
>> mos technology    sometimes good (even addresses) / always good
>> rockwell                 always bad (even addresses)  / always good (odd
>> addresses)
>> WDC                      not working both cases
>> bulgarian clone    not working both cases
>>
>> any idea ? I dont really know what to think...
> that makes no sense at all... it really shouldn't make a difference.
>


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Received on 2016-03-30 09:00:30

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