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???
07/25/05 12:50
Modified:
  07/25/05 13:18

Read: times


 
#97991 - no can do
Responding to: ???'s previous message
I want to interface 8052 with 22MHz crystall with 8255
no can do. You see, in the olden days when the king of diamonds were still a jack, the '51 ran with an 8 MHz clock or, if you were real adventurous maybe even 12 MHz. In addition these kinder gentler derivatives consumed 12 clocks per operation. Thus any schematic including the 8255 dates from the antiquity. In those days a fairy godmother made a nice, kind, gentle, thing called the Goldilocks 8255 which really loved to be fed with a gentle clock of 8 MHz. Now you take one of the newfangled 22 MHz speed demons and it just spy fire and eat Goldilocks.

Oh, well, there is no way the antique can keep up with a 22 MHz clock If you absolutotally have to use the antique, you need to lower your clock rate

Erik

PS: had you taken the time to "read" the datasheet, the above would have been clear to you.

I used the word "read", please do not delete for being offensive.

List of 39 messages in thread
TopicAuthorDate
8255 interfacing problem            01/01/70 00:00      
   well..            01/01/70 00:00      
      8255 interface problem            01/01/70 00:00      
         If you must use 8255            01/01/70 00:00      
            My datasheet says.....            01/01/70 00:00      
   Settle Erik!            01/01/70 00:00      
      8255 problem            01/01/70 00:00      
         hardware            01/01/70 00:00      
            adding to Steve..            01/01/70 00:00      
            Comment            01/01/70 00:00      
               Relic            01/01/70 00:00      
                  that was not 8255            01/01/70 00:00      
                     Actually....            01/01/70 00:00      
                        ot: 825x in PC            01/01/70 00:00      
                           Parallel port            01/01/70 00:00      
                              NOoooooooooooooooooooo            01/01/70 00:00      
                                 Ooops            01/01/70 00:00      
                                    OK I give it up! :-)            01/01/70 00:00      
                                       Just like            01/01/70 00:00      
                                 8255 in original PC            01/01/70 00:00      
               If I did not keep up with the times and            01/01/70 00:00      
                  Do your kids drive Segway?            01/01/70 00:00      
                     the real problem is not that the 82xx is            01/01/70 00:00      
                        Erik - A history lesson            01/01/70 00:00      
                           ok, even further back            01/01/70 00:00      
                              Picky, picky            01/01/70 00:00      
                                 are we getting there now?            01/01/70 00:00      
                                    Oh altight then :-)            01/01/70 00:00      
         More info needed            01/01/70 00:00      
   Pull up resistors.            01/01/70 00:00      
      Pullups            01/01/70 00:00      
   no can do            01/01/70 00:00      
      Yes he can!            01/01/70 00:00      
         does not make it current            01/01/70 00:00      
            my opinion...            01/01/70 00:00      
               did you not read            01/01/70 00:00      
                  Nope            01/01/70 00:00      
   8255 PROBLEM            01/01/70 00:00      
      10 Points            01/01/70 00:00      

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