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???
12/17/06 20:18
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 		 #129646 - re: back in the day
Responding to: ???'s previous message
Neil Kurzman said:
I recall 74LS and 74HCT Everyone used the pullups on Port 0 (10K SIP) They maay have been required bacck then?? I forget, I just code now.


Funny, I remember the same thing ... even though the data sheet says that Port 0 pull-ups weren't necessary, the 87C51 designs I did using LS573 needed 'em anyways. I never understood why. 4.7K SIP pullups did the trick.

-a

List of 45 messages in thread
TopicAuthorDate
Why would the OLD part get hot?            01/01/70 00:00      
   Could be            01/01/70 00:00      
      just to focus ...            01/01/70 00:00      
         Current consumption?            01/01/70 00:00      
      HMOS            01/01/70 00:00      
         Yes, they were warm ...            01/01/70 00:00      
            some special mode?            01/01/70 00:00      
               I know            01/01/70 00:00      
               I doubt there\'s a special mode involved            01/01/70 00:00      
                  BI NGO!            01/01/70 00:00      
                     Not yet, my friend ... but you\'re onto something            01/01/70 00:00      
                        doen memory lane            01/01/70 00:00      
                           it's all pretty confusing            01/01/70 00:00      
                              they all did            01/01/70 00:00      
   well ... the REAL question is ...            01/01/70 00:00      
   Have you tried using slow SRAM...            01/01/70 00:00      
      How about....            01/01/70 00:00      
         I'm not sure what that will tell me.            01/01/70 00:00      
      What do you believe that would do?            01/01/70 00:00      
         Step Back            01/01/70 00:00      
            Well, that's how it is ...            01/01/70 00:00      
   Some hints            01/01/70 00:00      
      Yes, that\'s so ...            01/01/70 00:00      
         Maybe            01/01/70 00:00      
            Intel doesn\'t care ...            01/01/70 00:00      
            O.K. ... so here\'s what I\'ve found ...            01/01/70 00:00      
               do you want to be stylish?            01/01/70 00:00      
                  Bipolar logic? Maybe            01/01/70 00:00      
                     Back in the day            01/01/70 00:00      
                        Pull-ups            01/01/70 00:00      
                           Dynamic logic may be the reason for the hot part            01/01/70 00:00      
                           That's what I find confusing            01/01/70 00:00      
                              pullups HCT and LS            01/01/70 00:00      
                                 74HCTMOS does not contain internal pull-ups            01/01/70 00:00      
                                 emitters vs resistors            01/01/70 00:00      
                           So, Kai, How did you arrive at 10K-ohms?            01/01/70 00:00      
                              No calculations, just a compromise            01/01/70 00:00      
                                 I haven't tried it with LS parts ... yet ...            01/01/70 00:00      
                                    throw away that databook :-)            01/01/70 00:00      
                                       Well, it's the old TTL book from TI ...            01/01/70 00:00      
                                          just a thought re LS pullup            01/01/70 00:00      
                                             That's the HCTLS from Samsung            01/01/70 00:00      
                        re: back in the day            01/01/70 00:00      
                           What about P2?            01/01/70 00:00      
                              No Just P0            01/01/70 00:00      

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