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???
10/09/06 07:45
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 		 #126033 - why?
Responding to: ???'s previous message
Richard Erlacher said:
[8255 replacement ...] What I'd expect is something that can operate with one-time setup, [...] I'd also expect it to handle hardware handshaking, which the 8255 can do.[...] I'm not saying this CAN'T be done, but nobody's pointed out how it SHOULD be done.


Well, the answer is maybe not what you'd expect, Richard, but an another quetion: WHY it should be done?

Who needs hardware handshaking, notabene bidirectional, on 8-bit buses (except "my professor asked me to do so")?
I don't say NOBODY, but those who do will certainly know better what to do - inclusive considering to use a 8255.

And as fast IO is concerned, I doubt the newbies would ever need more than 74xx573/74xx245.

JW


List of 174 messages in thread
TopicAuthorDate
How to extend the ports of 8051?            01/01/70 00:00      
   I2C, SPI, 1-Wire, CPLD            01/01/70 00:00      
      Why "avoid 8259"?            01/01/70 00:00      
         Why "avoid 8259"?            01/01/70 00:00      
            Hi            01/01/70 00:00      
         Hi            01/01/70 00:00      
      Examples            01/01/70 00:00      
   Choose an 8051 w. sufficient IO in the 1st place!            01/01/70 00:00      
      all 8051\'s have the same amount of I/O            01/01/70 00:00      
         list please            01/01/70 00:00      
            typo ... sorry ...            01/01/70 00:00      
         OK then, "derivative"            01/01/70 00:00      
         huh?            01/01/70 00:00      
            I think he means...            01/01/70 00:00      
               you're right, and that's the point, actually            01/01/70 00:00      
                  cause and effect            01/01/70 00:00      
   Clarification please            01/01/70 00:00      
      Clarification            01/01/70 00:00      
         Hi            01/01/70 00:00      
            Specifics ?            01/01/70 00:00      
      Hi            01/01/70 00:00      
   8255            01/01/70 00:00      
      Avoid 8255!            01/01/70 00:00      
         8255 Is Available in India            01/01/70 00:00      
            I learned the 8085 and 8255 in college            01/01/70 00:00      
               more number blindness?            01/01/70 00:00      
                  Yes            01/01/70 00:00      
                     Actually, it IS possible ... but you\'re right            01/01/70 00:00      
                        why?            01/01/70 00:00      
                        who said useless?            01/01/70 00:00      
            so the blind should lead the deaf?            01/01/70 00:00      
               somebody's got to do it!            01/01/70 00:00      
         What do you mean by "cumbersome?"            01/01/70 00:00      
      which antique store do you shop at?            01/01/70 00:00      
   FAQ            01/01/70 00:00      
      now THAT would be helpful to many!            01/01/70 00:00      
         nobody said so            01/01/70 00:00      
            too slow?            01/01/70 00:00      
               if you want a FAQ ...            01/01/70 00:00      
                  Input or Output            01/01/70 00:00      
                     Well ... the Motorola parts did that ... bitwise            01/01/70 00:00      
                        Port C            01/01/70 00:00      
   Hi Everyboody!            01/01/70 00:00      
   Port I/O of 8051            01/01/70 00:00      
      Serial and parallel I/O            01/01/70 00:00      
         As many as two?!            01/01/70 00:00      
            port expansion            01/01/70 00:00      
               Oops - you've been in that museum again!            01/01/70 00:00      
                  that I know but            01/01/70 00:00      
                     sure            01/01/70 00:00      
                        i have not and I can't            01/01/70 00:00      
                           sorry...            01/01/70 00:00      
                     WSI; Waferscale; ST; PSM; PSD            01/01/70 00:00      
               wotizit?            01/01/70 00:00      
                  wired or line            01/01/70 00:00      
                     I'd not call it a "pin extension"...            01/01/70 00:00      
                        I would            01/01/70 00:00      
      Requirements            01/01/70 00:00      
      FAQ            01/01/70 00:00      
         a good start, but woefully incomplete            01/01/70 00:00      
            Triscend - now Zylogic            01/01/70 00:00      
            "woefully incomplete", eh?            01/01/70 00:00      
               response            01/01/70 00:00      
                  there are some \"gotchas\"            01/01/70 00:00      
                     I used them before they became flash parts            01/01/70 00:00      
                        So, where's the link to the ST software?            01/01/70 00:00      
                           let a WSI user find that out            01/01/70 00:00      
                              There are no more WSI users ... there's no WSI            01/01/70 00:00      
                                 WSI usres-PSD usres OK            01/01/70 00:00      
                           Richard... What P/N you looking at?            01/01/70 00:00      
                              I just skimmed over the four most prominent ones            01/01/70 00:00      
                           Is this it?            01/01/70 00:00      
                     PSD/uPSD            01/01/70 00:00      
   A couple of Articles on embedded I/O            01/01/70 00:00      
      broken libks            01/01/70 00:00      
         fixed            01/01/70 00:00      
      informative article(s) but ...            01/01/70 00:00      
         CPLDs and FPGAs            01/01/70 00:00      
            differences            01/01/70 00:00      
               that's not really the issue...            01/01/70 00:00      
            They\'re available at no cost            01/01/70 00:00      
               the invasion of ther windows "programmers"            01/01/70 00:00      
            re: CPLDs and FPGAs            01/01/70 00:00      
               Andy PLEASE            01/01/70 00:00      
            I only promote stuff            01/01/70 00:00      
         FPGA/CPLD drawbacks            01/01/70 00:00      
            please make complete statements            01/01/70 00:00      
               @Erik: please read complete:            01/01/70 00:00      
                  giving examples does not exclude            01/01/70 00:00      
            well, that's a big maybe ...            01/01/70 00:00      
               an example            01/01/70 00:00      
                  voltage is not my choice            01/01/70 00:00      
                     where is the beef?            01/01/70 00:00      
                        it depends            01/01/70 00:00      
                           costs less, too.            01/01/70 00:00      
   consider this ...            01/01/70 00:00      
      but why skin a cat that is rotted? the fur will no            01/01/70 00:00      
         You keep saying that, but WHY?            01/01/70 00:00      
            NO WAY            01/01/70 00:00      
               I'm not from Missouri, but "SHOW ME"            01/01/70 00:00      
                  you have now visited Missouri            01/01/70 00:00      
                     waitaminute Erik...            01/01/70 00:00      
                        and my argument is            01/01/70 00:00      
                           your argument is fallacious            01/01/70 00:00      
                              once more mixing I/O mapped and MMIO            01/01/70 00:00      
                              OFF TOPIC but...            01/01/70 00:00      
                                 it\'s the disparity between rural and urban areas            01/01/70 00:00      
                                    I do not, BUT            01/01/70 00:00      
                           pins, lost&found            01/01/70 00:00      
                              a rephrase, a question and a subject issue            01/01/70 00:00      
                                 technically            01/01/70 00:00      
                                    mixing once more            01/01/70 00:00      
                                 You're being either crazy or stupid, Erik            01/01/70 00:00      
                                    I think the crazy one is you, Richard            01/01/70 00:00      
                                       I'm a seasoned man ...            01/01/70 00:00      
                                          Same back at ya            01/01/70 00:00      
                                             Now we're into semantics            01/01/70 00:00      
                                                Now you are completely off the rocker. Who, more            01/01/70 00:00      
                                                   Wake up!            01/01/70 00:00      
                                                      that is a BLATANT LIE            01/01/70 00:00      
                                                         Good grief, Erik! It's not personal ...            01/01/70 00:00      
                                                            YES, YES and YES. I even had to code it in assemb            01/01/70 00:00      
                                                         you could state that explicitly....            01/01/70 00:00      
                                             I've tried to be diplomatic            01/01/70 00:00      
                                                I'll try it, too            01/01/70 00:00      
                                                   the IIC as an alternative            01/01/70 00:00      
                                                      As an alternative, but only sometimes            01/01/70 00:00      
                                                         two viewpoints            01/01/70 00:00      
                                                         SATA            01/01/70 00:00      
                                                            I\'d like to meet...            01/01/70 00:00      
                                                               My point            01/01/70 00:00      
                                                               Parallel works off-board as well            01/01/70 00:00      
                                                            very true, but it doesn\'t apply            01/01/70 00:00      
                                                         try THAT with the 8255            01/01/70 00:00      
                                                            Erik, it might surprise you to learn ...            01/01/70 00:00      
                                                               WHAT            01/01/70 00:00      
                                                                  Erik, in response to WHAT            01/01/70 00:00      
                                                               that implies serial, in which case the 8255            01/01/70 00:00      
                                                                  I said is was parallel-interfaced ...            01/01/70 00:00      
                                                                     Please find the word 'parallel', I may be going bl            01/01/70 00:00      
                                                                        You're right, I left it out ...            01/01/70 00:00      
                                                                           The title of nthe thread is "How to extend the por            01/01/70 00:00      
                                                                              Yes, it's HOW TO and not HOW NOT TO ...            01/01/70 00:00      
                                                                                 attaching an old ratteling caboose to a high speed            01/01/70 00:00      
                                                         not that slow - especially compared to the 8255            01/01/70 00:00      
                                                            Erik, look at the datasheet ...            01/01/70 00:00      
                                                               how do you propose to \"get it in\" at that speed            01/01/70 00:00      
                                                                  Yes, this needs clarification            01/01/70 00:00      
                                                                     no, you don't            01/01/70 00:00      
                                                                        Erik, Once again, you've brought too much to            01/01/70 00:00      
                                                                           nope, there are plenty of boards with (sorry, I kn            01/01/70 00:00      
                                                                              Well, show me ... it\'s proven untrue so far.            01/01/70 00:00      
                                                                                 I am really curious what you are making where a            01/01/70 00:00      
                                                                                    Been there, done that ...            01/01/70 00:00      
                                                                                       now you lose me            01/01/70 00:00      
                                                                                          I don\'t like \'em.            01/01/70 00:00      
                        Jan ... DIGIKEY's not always the cheapest            01/01/70 00:00      
                           of course, if you can sell the sh eh stuff            01/01/70 00:00      
                     the datasheet says ...            01/01/70 00:00      
                        are you mixing cement in a futile attempt to cast            01/01/70 00:00      
                           go back to school, Erik!            01/01/70 00:00      
                           go back to school, Erik!            01/01/70 00:00      
                              I say, you say            01/01/70 00:00      
                                 Erik, go back and read the whole thing            01/01/70 00:00      
                                    had Peter IlyitchTscaikowsky lived ...            01/01/70 00:00      
                                       one more... :-)            01/01/70 00:00      
                                          hve you see any post stating that?            01/01/70 00:00      
                                             yes. Richard's... :-)            01/01/70 00:00      
                                                and that was because ...            01/01/70 00:00      
   Why is this so endlessly fascinating?            01/01/70 00:00      
      to Jez            01/01/70 00:00      
         i dunno            01/01/70 00:00      
   "Extending Input/output"            01/01/70 00:00      
      "Extending Input/output"            01/01/70 00:00      

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