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???
01/23/06 19:41
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 		 #108124 - Memory Map
Responding to: ???'s previous message
Please tell me if I am wrong.
The OP only need the /PSEN to enable the EEPROM because the program is there (8032). The 8255 is in the external data memory space, then you can use /RD and /WR and A15 to /CS to enable it. Now, if you use A0 and A1 of the 8032 with A0 and A1 of the 8255, then your 8255 may be is in the following address:

1000 0000 0000 0000 = 8000H

1000 0000 0000 0001 = 8001H

1000 0000 0000 0010 = 8002H

1000 0000 0000 0011 = 8003H

F011 is an address of the 8255, if you note that the A14 - A2 lines are don´t care.

1111 0000 0001 0001 = F011H but this is the address of the port b.

I don´t know exactly but it sounds like a memory map trouble. Please check your hardware and give us a diagram to see.

Roberto Muñoz

List of 55 messages in thread
TopicAuthorDate
please help me            01/01/70 00:00      
   Clock freq            01/01/70 00:00      
   Reset ?            01/01/70 00:00      
   please help me            01/01/70 00:00      
      Probe            01/01/70 00:00      
         8255 PROBLEM            01/01/70 00:00      
            Reset 8255            01/01/70 00:00      
   Memory Map            01/01/70 00:00      
   please help me            01/01/70 00:00      
      Scope            01/01/70 00:00      
         8255 address?            01/01/70 00:00      
   Memory Map part 2            01/01/70 00:00      
   isn't this fun            01/01/70 00:00      
      for once, I've got to agree            01/01/70 00:00      
         please help me            01/01/70 00:00      
            8255 - EXTERMINATE!!!!            01/01/70 00:00      
               Cool            01/01/70 00:00      
                  Some I/O expansion, some nostalgia            01/01/70 00:00      
                     Even Better 74xx573            01/01/70 00:00      
                        or - even better?            01/01/70 00:00      
               more easily said than done            01/01/70 00:00      
                  selling "haystacks" is criminal            01/01/70 00:00      
                     Huh?            01/01/70 00:00      
                        see ad in EE times            01/01/70 00:00      
                           Hobbyist            01/01/70 00:00      
                              max 7103            01/01/70 00:00      
                                 location            01/01/70 00:00      
                           $13? For what? What pitch, tolerance?            01/01/70 00:00      
                              He's English.            01/01/70 00:00      
                                 None, I hope            01/01/70 00:00      
                                    Reliable ?            01/01/70 00:00      
                                       Yes, I like 'em too ...            01/01/70 00:00      
                                          Never wire wrapped            01/01/70 00:00      
                                             You don't have to wire-wrap to benefit            01/01/70 00:00      
                              read the ad            01/01/70 00:00      
                  Atmel and Phillips            01/01/70 00:00      
            please help me, why on earth should we            01/01/70 00:00      
   please help me            01/01/70 00:00      
      for the Philips P89V51Rx2 and the P89C66            01/01/70 00:00      
         Atmel too            01/01/70 00:00      
            Are You Sure            01/01/70 00:00      
               Don't worry            01/01/70 00:00      
   Understand your system            01/01/70 00:00      
   please help me            01/01/70 00:00      
      Please don't answer            01/01/70 00:00      
         What is the clock of your system            01/01/70 00:00      
            Maybe you should use the 8155?            01/01/70 00:00      
               if it has to be some such thing, then by            01/01/70 00:00      
   Why?            01/01/70 00:00      
      never heard of 8155            01/01/70 00:00      
         well ... few of us have heard of it, but            01/01/70 00:00      
            RIOT            01/01/70 00:00      
               OK ... but that's not what the OP wants.            01/01/70 00:00      
                  There is one enormous difference between            01/01/70 00:00      
   Maybe this will help.            01/01/70 00:00      

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