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???
02/23/07 14:53
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 		 #133548 - ...
Responding to: ???'s previous message

Then an Intel-made 8051 microcontroller will have DPTR set to 0.

so then I guess it is safe to assume that a datasheet is correct.


If I was to hard-code a rom, I would not assume that any register was having a pre-determined value. It would be safer to initialize yourself all registers you need to have initialized.


In my code, I only depend on DPTR being zero on every reset. Once my code runs, the contents of P1 will be stored at the memory location set by DPTR. Then DPTR increments, so that the next byte is stored.


After all, if you do not want to depend on programmable devices, why depend on that fact?

I'm trying to use the fewest number of chips for a guaranteed working system. If I added "mov DPTR,0", then I might need more chips to decode the logic coming out of the decoder 74HC138.

For now, I am relying on DPTR to be 0.

List of 96 messages in thread
TopicAuthorDate
Boolean Algebra with "dont cares"            01/01/70 00:00      
   I do not fully get your applicatiojn, but            01/01/70 00:00      
      Let me explain            01/01/70 00:00      
   Karnaugh Mapping            01/01/70 00:00      
      longer?            01/01/70 00:00      
         8 times is longer?            01/01/70 00:00      
            I explained it            01/01/70 00:00      
               a square wheel is not that easy to make, is it?            01/01/70 00:00      
               Do you understand Karnaugh Mapping?            01/01/70 00:00      
   theres a very old program called espresso            01/01/70 00:00      
   also remember logic minimisation            01/01/70 00:00      
   Don't Cares            01/01/70 00:00      
      I don't think he needs an RS232 receiver            01/01/70 00:00      
         Well spotted            01/01/70 00:00      
            Deja Vu            01/01/70 00:00      
               Everything old is new again!            01/01/70 00:00      
                  For the paranoid...            01/01/70 00:00      
                     I have made my decision            01/01/70 00:00      
                        depending...            01/01/70 00:00      
                           yes and yes            01/01/70 00:00      
                              DPTR initialized            01/01/70 00:00      
                                 ...            01/01/70 00:00      
                                    fewest number of chips            01/01/70 00:00      
                                       You can do it with TWO chips.            01/01/70 00:00      
                                    You keep saying that!            01/01/70 00:00      
                                       Well ... he's on a crusade now ... let him be            01/01/70 00:00      
                                          ok            01/01/70 00:00      
                                             Common approach            01/01/70 00:00      
                                                I have a different idea            01/01/70 00:00      
                                                   that square wheel will get you in the ditch in 5 m            01/01/70 00:00      
                                                      No Sync -- The Same            01/01/70 00:00      
                                                         but            01/01/70 00:00      
                                                            thanks to Mr. Gates, that will not work            01/01/70 00:00      
                                                               at least I try.            01/01/70 00:00      
                                                                  driving your car into a tree also "can be done"            01/01/70 00:00      
                                                                     ...            01/01/70 00:00      
                                                                        I would never pay for something with 47 chips wher            01/01/70 00:00      
                                                                        well anyroad up            01/01/70 00:00      
                                                                        Proving one is crazy            01/01/70 00:00      
                                                                           Russell, you forgot the REAL issue            01/01/70 00:00      
                                                   just once            01/01/70 00:00      
                                 give him a a break ... he's using the INTEL part            01/01/70 00:00      
                        CrazyROM2 Still 15-18 Chips            01/01/70 00:00      
                           Practical? Credible?            01/01/70 00:00      
                              Impractical and Incredible            01/01/70 00:00      
                                 These guys knew what they were doing!            01/01/70 00:00      
                           That code is pretty much what I use            01/01/70 00:00      
      answer            01/01/70 00:00      
         Remove the blinkers!            01/01/70 00:00      
            A light dawns?            01/01/70 00:00      
   Don't cares are Dangerous Here            01/01/70 00:00      
      Now there's the thing...            01/01/70 00:00      
         Mike S I wish you a lot of fun            01/01/70 00:00      
   One 74154 and a handful of diodes            01/01/70 00:00      
      omg            01/01/70 00:00      
         Depends on buffer...            01/01/70 00:00      
            so does using ROM banks not make the use of a ROM            01/01/70 00:00      
               Used to have one...            01/01/70 00:00      
   has anyone ever 'lost' a ROM?            01/01/70 00:00      
      Yea, but I found it later :)            01/01/70 00:00      
      Lost ROMs            01/01/70 00:00      
         No part is failure-proof            01/01/70 00:00      
            statistical reliability issues            01/01/70 00:00      
               it's a learning experience ... [sigh]            01/01/70 00:00      
                  as usual, Mike replied "that is not what I want"            01/01/70 00:00      
                     well, maybe not zero ...            01/01/70 00:00      
                        ah, now I understand why Mike is doing this            01/01/70 00:00      
                           Buggy Whip Pricing            01/01/70 00:00      
                              oh, well            01/01/70 00:00      
                                 Maybe he should be left to his own devices            01/01/70 00:00      
                                    I made a better decision            01/01/70 00:00      
                                       the wheel is still square            01/01/70 00:00      
                                       why nop?            01/01/70 00:00      
                                          correction            01/01/70 00:00      
                                             answer            01/01/70 00:00      
                                                another question            01/01/70 00:00      
                                                   something else            01/01/70 00:00      
                                                      and I should have added...            01/01/70 00:00      
                                                         hard-coded            01/01/70 00:00      
                                       a couple of \'138\'s should do it            01/01/70 00:00      
                                          answer            01/01/70 00:00      
                                             not the first, more like #237654            01/01/70 00:00      
                                             "Invent"- Try 8052-BASIC            01/01/70 00:00      
                                       Just a thought            01/01/70 00:00      
                                       No thanks to anyone            01/01/70 00:00      
                                          Let the boy flounder ... he'll figure it out!            01/01/70 00:00      
                                          a bit of a chuckle?            01/01/70 00:00      
                                             sooner or later ...            01/01/70 00:00      
                                                you may be right :)            01/01/70 00:00      
                                                if I must lower my speed for programming, I will            01/01/70 00:00      
                                                   Capacitors on the write line            01/01/70 00:00      
                                                      NAAH            01/01/70 00:00      
                                                         anyone tell ya I have a slower clock too?            01/01/70 00:00      
                                                            Do you mean a crystal?            01/01/70 00:00      
                                                               it may            01/01/70 00:00      
   So, Mikey ... have you finally wised up?            01/01/70 00:00      

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