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???
06/06/06 07:33
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 		 #117836 - code?
Responding to: ???'s previous message
Richard Erlacher said:
Starting with the code. There's probably just something out of place.


The reasoning behind my questions:

I am staring at that test.asm long enough to find absolutely nothing wrong. This leaves me with the following hypotheses:
  1. faulty way from .asm to .hex
  2. faulty "burning" of the chip
  3. buggy chip
  4. faulty chip
Items 1 and 2 I find unprobable, as the test.asm is relatively complex and it seems it works - except the movx returns "incorrect" value. Item 4 you (and also me) find improbable. It leaves us with item 3. We know that the 420 was something of a "prerelease", with a couple of known bugs. It makes me believe there might be more. Particularly, I would accuse ORL on PMR first :-)

And, sorry, I can't try, I don't have a 420; but I tried '450 with BASIC52 running from the XRAM and it did work OK. I used
Save This Code
PMR   EQU   0C4h
...
      mov   PMR,#03h
(don't ask me why... :-o )

JW


PS.: external memory access can be detected as activity on /WR and/or /RD pins


List of 67 messages in thread
TopicAuthorDate
DS89C420 internal SRAM Access question            01/01/70 00:00      
   Timed access            01/01/70 00:00      
      Re: Timed access            01/01/70 00:00      
         Lacking ?            01/01/70 00:00      
            Re: Lacking            01/01/70 00:00      
   dunno            01/01/70 00:00      
      Re: dunno            01/01/70 00:00      
         lots of features to track            01/01/70 00:00      
   Example Code            01/01/70 00:00      
      Dallas SRAM Access            01/01/70 00:00      
   Update / Further Puzzle            01/01/70 00:00      
      False Alarm            01/01/70 00:00      
         A bug, maybe?            01/01/70 00:00      
            Isn't that CPU EOL (or not for new des?)            01/01/70 00:00      
               Yes, it's been replaced but he has it.            01/01/70 00:00      
                  Not Quite EOL but thats next ...            01/01/70 00:00      
                     Could be a disappointment            01/01/70 00:00      
                  how are you going to know if the problem            01/01/70 00:00      
                  Damned with faint praise!            01/01/70 00:00      
                     Clearly it's not for production            01/01/70 00:00      
                        Is there a difference between IAP & ISP?            01/01/70 00:00      
                           what I understand is            01/01/70 00:00      
                              DS89C4x0 IAP/ISP explained            01/01/70 00:00      
                           Final Update            01/01/70 00:00      
                              Try this            01/01/70 00:00      
                                 Re: Try this            01/01/70 00:00      
                                    It may be time for a different specimen            01/01/70 00:00      
                                       Re: new specimen            01/01/70 00:00      
                                          huh?            01/01/70 00:00      
                                             not enough benefit in replacing            01/01/70 00:00      
                                          I've been at this a LONG time ...            01/01/70 00:00      
                                    what does it return            01/01/70 00:00      
                                       returns 0x00            01/01/70 00:00      
                                          probably, but why?            01/01/70 00:00      
                                          I doubt you have to connect 'em            01/01/70 00:00      
                                              do not know what ISTR is            01/01/70 00:00      
                                                what it means            01/01/70 00:00      
                                                me either            01/01/70 00:00      
                                                   before you "move on"            01/01/70 00:00      
                                          oscillscope             01/01/70 00:00      
                                             it's not clear how a 'scope will help            01/01/70 00:00      
                                                Well a 'scope would ...            01/01/70 00:00      
                                                   exactly ... so why not have another look            01/01/70 00:00      
                                                      code?            01/01/70 00:00      
                                                         What about SFR definitions?            01/01/70 00:00      
                                                            SFR Def            01/01/70 00:00      
                                                            SFR was defined            01/01/70 00:00      
                                                               bad idea            01/01/70 00:00      
                                                                  Yep, it leads to confusion!            01/01/70 00:00      
                                    but...            01/01/70 00:00      
                                       confusion            01/01/70 00:00      
                                          That was what I wondered, too.            01/01/70 00:00      
                                             So ... What about it?            01/01/70 00:00      
                                             Clear a few things up            01/01/70 00:00      
                        wrong way around            01/01/70 00:00      
                     Most the time..            01/01/70 00:00      
                        That's undoubtedly the case.            01/01/70 00:00      
   Matthew, I am curious about something            01/01/70 00:00      
      Answer as best I can            01/01/70 00:00      
         It's still not clear ...            01/01/70 00:00      
            hmmm try some more            01/01/70 00:00      
               I don't think I'd try that ...            01/01/70 00:00      
                  Re:            01/01/70 00:00      
                     It's not rude ...            01/01/70 00:00      
                        Now ... here's what I did ...            01/01/70 00:00      
               test.asm once more            01/01/70 00:00      
                  Some more questions            01/01/70 00:00      

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