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???
03/28/06 16:27
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 		 #113310 - On the busses
Responding to: ???'s previous message
Roberto said:
No, there are 65536 lacations for code and 65536 locations for data.

To be really pedantic, there are 64K locations for code, and 64K locations for external data... ;-)

Kai Klaas said:
And how many address buses are there?

Only one address bus - but accesses to the Code locations are "qualified" by /PSEN, and accesses to the external Data locations are "qualified" by /RD or /WR

Ok, I shouldn't have mentioned "locations", but "addresses".

"Locations" are fine:
  • when your Code memory is enabled (by /PSEN), its locations are accessible;
  • when your external Data memory is enabled (by /RD or /WR), its locations are accessible.

    In total, there are 128K locations - 64K in the Code memory, and a separate 64K in the external Data memory!

    See p6 in Chapter 3 of the "bible".

    Chapter 3; 80C51 family hardware description.
    http://www.semiconductors.philips.com/acrobat/v...WARE_1.pdf


    • List of 58 messages in thread
    TopicAuthorDate
    How to decoder the memory address?            01/01/70 00:00      
       decoding already inside            01/01/70 00:00      
          That's not fair!            01/01/70 00:00      
             ???            01/01/70 00:00      
                Maybe unfair was the wrong way to put it            01/01/70 00:00      
                   why Flash esoteric ???            01/01/70 00:00      
                      So ... where's the decoding?            01/01/70 00:00      
                         decoding in practice            01/01/70 00:00      
                            This is not a personal attack, Peter            01/01/70 00:00      
                               actually            01/01/70 00:00      
                                  I don't disagree            01/01/70 00:00      
                                     hardly            01/01/70 00:00      
                                        what he asked was:            01/01/70 00:00      
                               R. E            01/01/70 00:00      
                                  Not exactly            01/01/70 00:00      
                                      Sorry Richard I was a little more            01/01/70 00:00      
                                  there is an ignore function available            01/01/70 00:00      
                                     that is how I currently do it            01/01/70 00:00      
                                        drop the flat mode, go threaded            01/01/70 00:00      
       There's a way, once you've decided            01/01/70 00:00      
       The first step            01/01/70 00:00      
          Requirements, a most important variable            01/01/70 00:00      
             I'm not a machine            01/01/70 00:00      
       RE: How to decoder the memory address?            01/01/70 00:00      
          it's bible time            01/01/70 00:00      
       Don't look bad each others please            01/01/70 00:00      
          74HC138            01/01/70 00:00      
          why do you refuse to read "the bible"            01/01/70 00:00      
             What chapter will answer his question?            01/01/70 00:00      
                I never answer that            01/01/70 00:00      
                   Who's joy? Yours??            01/01/70 00:00      
                      places "the bible"            01/01/70 00:00      
                         Just answer the question            01/01/70 00:00      
                            then why did you not give him an answer            01/01/70 00:00      
                               because I'm just as bad as you, Erik            01/01/70 00:00      
             Not this time            01/01/70 00:00      
                You're right, and he knows it            01/01/70 00:00      
          Interesting link            01/01/70 00:00      
          Example            01/01/70 00:00      
          questions, guesses and comments            01/01/70 00:00      
             Now, was that so hard?            01/01/70 00:00      
                silliness was never here            01/01/70 00:00      
                   Well, perhaps not, but ...            01/01/70 00:00      
                      So when?            01/01/70 00:00      
          RE: Don't look bad each others please            01/01/70 00:00      
       Don't look bad each others please            01/01/70 00:00      
       I do not understand            01/01/70 00:00      
       Addressing 101            01/01/70 00:00      
       Why using this processor pins left...?            01/01/70 00:00      
          What chips?            01/01/70 00:00      
          What is the problem?            01/01/70 00:00      
             Explaination            01/01/70 00:00      
                I just remembered 22V10            01/01/70 00:00      
                Be careful            01/01/70 00:00      
                   How many address buses do you see?            01/01/70 00:00      
                      On the busses            01/01/70 00:00      
                         The only purpose was...            01/01/70 00:00      
                            The question has been well addressed            01/01/70 00:00      

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