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???
09/15/05 13:32
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#101128 - re: 2 Hints!
Responding to: ???'s previous message
hi,

Reza Javan said:
Hello Oleg
MOV  A,P1        ; load current state of bits 0...3
..
..
XRL  P1,A        ; change not masked bits
Is there any need to mov p1,#0ffh before first line?

No, probably not. Reading port into Acc returns value from pins of port. It does not depend on how pins are configured - as input or output ones.

Before it i thought in mathematical operation,first operand must only be accumlator!

Yes, the arithmetic operations have this limitation. Here we use logical operation which is free from this rule.

Regards,
Oleg

List of 23 messages in thread
TopicAuthorDate
Week puzzle IV            01/01/70 00:00      
   In my opinion            01/01/70 00:00      
      no            01/01/70 00:00      
         Bufff!! then TRB            01/01/70 00:00      
            Me and my shadow, walking down the aven            01/01/70 00:00      
               You & your shadow            01/01/70 00:00      
                  http://www.coleporter.org/            01/01/70 00:00      
                     it's a hint            01/01/70 00:00      
   Well            01/01/70 00:00      
      you got it            01/01/70 00:00      
         Just OR with ones            01/01/70 00:00      
            how?            01/01/70 00:00      
   a simple solution:            01/01/70 00:00      
      not atomic            01/01/70 00:00      
         atomic not possible in general !            01/01/70 00:00      
   My solution!            01/01/70 00:00      
      Wrong            01/01/70 00:00      
      not atomic            01/01/70 00:00      
         Ok, here is the shadow            01/01/70 00:00      
            only four bits            01/01/70 00:00      
               2 Hints!            01/01/70 00:00      
                  Oh boy, do you need some bible time            01/01/70 00:00      
                  re: 2 Hints!            01/01/70 00:00      

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