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???
02/28/07 13:26
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 		 #133927 - I made a better decision
Responding to: ???'s previous message
no thanks to anyone, I came up with this code:


wt:
jbc IE0,wt3
ljmp wt
nop
wt3:
anl A,0
orl A,P1
movx @DPTR,A
inc dptr
ljmp wt


This allows me to make the decoding logic using 6 IC packages: 2 triple 3-input nands, 1 dual 4-input nand, 2 74HC138 decoders, and 1 74HC245 buffer.

I'll probably make changes, but no local store in the area has an 74HC154 or 74HCT154 which would be ideal.

I still might be crazy in doing this project, but at least I learn. I must say, at least I don't have to pay money for a person to shoot a bunch of words at me which I soon forget.

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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