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???
09/27/09 01:17
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 		 #169182 - There often are huge speed differences
Responding to: ???'s previous message
Richard Erlacher said:
[...] yet the big 32-bitters aren't really any faster, since they most often don't have 4-bit-data-handling instructions, and therefore have to waste a lot of time processing the bytes and nybbles.

Most 32-bitters have barrel-shifters so they shift multiple steps in constant time. And a number of them have good hw support for the four data bits, allowing the processor to just issue a DMA transfer resulting in 32-bit memory accesses in the background.


List of 55 messages in thread
TopicAuthorDate
I've asked this before ... but ...            01/01/70 00:00      
   Is this specifically 8051?            01/01/70 00:00      
      specifically with 805x and NO SD-specific hardware on-chip            01/01/70 00:00      
         There often are huge speed differences            01/01/70 00:00      
   Yep I have            01/01/70 00:00      
      I'd be interested in that ...            01/01/70 00:00      
         Ill send you a schematic            01/01/70 00:00      
            What do points mean?            01/01/70 00:00      
            Well, I haven't seen it ... yet            01/01/70 00:00      
               Oh dear; I hope this wasn't Jez, then...            01/01/70 00:00      
   How fast?            01/01/70 00:00      
      I'm using an old, but relatively complete, spec            01/01/70 00:00      
         "external" hardware            01/01/70 00:00      
            Yes, that would be nice ...            01/01/70 00:00      
         50MBps            01/01/70 00:00      
            That's what the capital B means ...            01/01/70 00:00      
               You assume too much            01/01/70 00:00      
                  It's like that other nomenclature issue I keep mentioning            01/01/70 00:00      
                     Sad, but true            01/01/70 00:00      
               25MHz * 4bit = 12.5MB/s            01/01/70 00:00      
                  correct            01/01/70 00:00      
                  Now I'm confused ... as you can see ...            01/01/70 00:00      
                     someplace to put spec's            01/01/70 00:00      
                        It's a two-edged sword            01/01/70 00:00      
                           True, but..            01/01/70 00:00      
                              Published spec's are in the public domain            01/01/70 00:00      
                                 No, that's not true            01/01/70 00:00      
                                    It depends on how the IP is used, doesn't it?            01/01/70 00:00      
                                       No, it doesn't.            01/01/70 00:00      
                                          Not public domain            01/01/70 00:00      
                                             Quite so!            01/01/70 00:00      
                                             Copyright Term and the Public Domain in the United States            01/01/70 00:00      
                                                They have the "right" but not the cause            01/01/70 00:00      
                                                   Letter of the law            01/01/70 00:00      
                                                      Let me ask you something ...            01/01/70 00:00      
                                                         I didn't say that            01/01/70 00:00      
                                                   They have the right            01/01/70 00:00      
                                                      When was the last time you saw a written copyright?            01/01/70 00:00      
                                                         See previous examples!            01/01/70 00:00      
                                                            Whose interests are "protected"?            01/01/70 00:00      
                                                               Information owners            01/01/70 00:00      
                                                                  ?            01/01/70 00:00      
                                                                     Life isn't fair            01/01/70 00:00      
                                                               What the thread is about? SD Card or CopyRights!!!            01/01/70 00:00      
                                                                  There's a reason for that ...            01/01/70 00:00      
                                                                     Lots of interests in SD, but danger involved in sharing            01/01/70 00:00      
                                                         last time I saw a written copyright ...            01/01/70 00:00      
                                                            No need for long legalese            01/01/70 00:00      
                                                               True, but ...            01/01/70 00:00      
                                                            That's the boilerplate to which I referred            01/01/70 00:00      
                                                               the band won            01/01/70 00:00      
                                                      Ooops!            01/01/70 00:00      
   I forgot sorry            01/01/70 00:00      
      That was what ... 6 weeks ago?            01/01/70 00:00      
   SD/SDIO host controller chips            01/01/70 00:00      

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