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32496Re: [midatlanticretro] EDN article: "The Serial Port: It Just Keeps Going"

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  • Neil Cherry
    Sep 23 4:20 PM
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      On 09/23/2013 06:34 PM, joshbensadon wrote:
      > >> Regarding the inventor of the 1488/1489, try to contact him, it would be
      >
      > >> really cool to know more about the origins of these chips.
      >
      > >Yes, that's a good idea.
      >
      > I have a question about those chips, perhaps you or someone in this group might know the
      > answer. Why did they create them with a NAND function? I mean, wouldn't it have been
      > better if these RS-232 drivers/receivers would have been 6 per package instead of 4? In
      > every design I've ever seen, the two NAND inputs are simply tied together.

      Nand? I always thought of that as enable/disable so you could put into
      Hi-Z mode. This would allow more than one device on the line though I've
      never seen them used that way.

      BTW, I though we just used CMOS before this (triple voltage CMOS as
      I recall: +/- 15v,-5v and gnd). And yes the 88/89 chips were great for
      self sacrifice. I thought that was s design feature (really we used it
      as such). If lightening struck, swap the chips and you were usually good
      to go. Except for that board that came back mostly black ...

      --
      Linux Home Automation Neil Cherry ncherry@...
      http://www.linuxha.com/ Main site
      http://linuxha.blogspot.com/ My HA Blog
      Author of: Linux Smart Homes For Dummies
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