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???
10/10/06 21:34
Modified:
  10/10/06 21:37
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 		 #126149 - It depends on what your definition of response is.
Responding to: ???'s previous message
When I refer to the speed of I/O, I'm referring to the response times of the I/O hardware, i.e. how long it takes the output hardware to transfer data from its inputs to its outputs. That time is normally measured in nanoseconds. When a hardware handshake is required, it's possible to build external hardware that responds to an input strobe, for example, within a very short time, and issues an acknowledge strobe. The i8255 manages those strobes for you using port 'C' bits. It does that with no controller burden aside from the initial setup, and can generate a timely interrupt if desired.

No 805x that I know of is so slow that it's incapable of transferring data from its data bus to external hardware within a microsecond or so, regardless of its supply voltage or system clock.

To what, Steve, do you refer when you say "not possible" in your comment?

RE


List of 69 messages in thread
TopicAuthorDate
Long Division            01/01/70 00:00      
   teach the kids the slide rule!!            01/01/70 00:00      
      I don't know about that slide-rule ...            01/01/70 00:00      
         not the point            01/01/70 00:00      
   We Homeschool our kids            01/01/70 00:00      
      Not "foundational"            01/01/70 00:00      
         8255 is DEAD            01/01/70 00:00      
            no, not "industry professionals "            01/01/70 00:00      
            Stupid though            01/01/70 00:00      
               Over here it was Whole Language Reading            01/01/70 00:00      
                  On the other hand ...            01/01/70 00:00      
                  Plus ca change            01/01/70 00:00      
            I am not so sure            01/01/70 00:00      
            the purpose of teaching 8255...            01/01/70 00:00      
               high-speed my butt            01/01/70 00:00      
                  have you read the footnote?            01/01/70 00:00      
            0xDEAD            01/01/70 00:00      
            what does DEAD mean?            01/01/70 00:00      
               some like kicking a dead horse            01/01/70 00:00      
                  that's why you don't do electronics as a hobby.            01/01/70 00:00      
                     not exacttly            01/01/70 00:00      
         It's a component of a microcomputer            01/01/70 00:00      
            memory is one thing, today is another            01/01/70 00:00      
               That\'s not quite true ...            01/01/70 00:00      
                  6 vs 2 clock            01/01/70 00:00      
                     I wasn't considering them ...            01/01/70 00:00      
                        but there is            01/01/70 00:00      
                           No doubt about it            01/01/70 00:00      
                              IIC recently upgraded to 1MHZ and I have run            01/01/70 00:00      
                                 Interesting ... what operates at that rate?            01/01/70 00:00      
                                    this and a HUH?            01/01/70 00:00      
                                       You've referred to that before, Erik ...            01/01/70 00:00      
                                          you are missing half the story and mixing            01/01/70 00:00      
                                             depends on what you compare            01/01/70 00:00      
                                                comparing            01/01/70 00:00      
                                                   some are ruled out ...            01/01/70 00:00      
                                                      the birth has happened            01/01/70 00:00      
                                                         uPSDs            01/01/70 00:00      
                                                         in the prototype area or ...            01/01/70 00:00      
                                                            Richard, how old are you?            01/01/70 00:00      
                                                               PSDs            01/01/70 00:00      
                                                                  isn't EVERYTHING ST makes with an MCU a uPSD?            01/01/70 00:00      
               Intel called them single-chip microcomputers            01/01/70 00:00      
                  greedy, are we?            01/01/70 00:00      
                     Yep ... greedy ... I need a 48KB buffer ...            01/01/70 00:00      
         fast I/O            01/01/70 00:00      
            Can''t do it            01/01/70 00:00      
               typo            01/01/70 00:00      
               It depends on what your definition of response is.            01/01/70 00:00      
                  I read the post the same way as Steve            01/01/70 00:00      
                     Perhaps, but the i8255 does it automatically            01/01/70 00:00      
                  No time            01/01/70 00:00      
                     That was my point!            01/01/70 00:00      
                        long story short            01/01/70 00:00      
                           move?            01/01/70 00:00      
                           take a look ...            01/01/70 00:00      
                        where do you buy that?            01/01/70 00:00      
                           Normally, the board determines that            01/01/70 00:00      
                              where did he say that?            01/01/70 00:00      
                                 Yes, it's a mystery ... but ...            01/01/70 00:00      
   Teaching Numeracy            01/01/70 00:00      
      Numeracy            01/01/70 00:00      
         That's where lots of education is lost ...            01/01/70 00:00      
   Two ways to do math            01/01/70 00:00      
   The 3 Rs            01/01/70 00:00      
      The middle \'R\'            01/01/70 00:00      
         when I were trined to be a spy ..            01/01/70 00:00      
            Fast block lettering            01/01/70 00:00      
               practice, practice            01/01/70 00:00      

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