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6679Re: Free Running .pdf

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  • Saundby
    Apr 5, 2010
      --- In cosmacelf@yahoogroups.com, "RickC" <ricortes@...> wrote:
      > IMO: A single resistor on the power supply line to the LEDs would be a good idea just in case someone tries running it at 10V or so. One resistor would be enough. Some dimming when multiple LEDs are on may happen but it will add to the effect.
      > Rick


      What I've done is specify a power supply range from 3.0 to 6.0VDC, and added a note about clock speeds/Vdd voltage.

      I also caught a missing "dot" at an intersection. While I had the document open I enlarged the text a bit. In hardcopy, it was pretty small, even for my new glasses. ;)

      Anything else, let me know.


      > --- In cosmacelf@yahoogroups.com, Mark Graybill <saundby@> wrote:
      > >
      > > OK, I've replace the old erroneous file free-run with a new one.
      > >
      > > If anyone would like to do a sanity check on it for me, I'd appreciate
      > > it. I believe I got everything right this time, but my new digital
      > > camera isn't sophisticated enough to generate a schematic from taking
      > > a picture of my breadboard yet, so I've got a chance to introduce
      > > plenty of errors when I manually draw up a schematic. ;)
      > >
      > > What I use a free run circuit for is testing a CPU to make sure it's
      > > basically functional. I also will usually build up a free run circuit
      > > whenever I pick up a new processor as a way of familiarizing myself
      > > with it's pinout, and any requirements to get it running such as
      > > making sure all the /RESET, HOLD, INTR, /WAIT, /CLEAR, /DMA...etc
      > > lines are held in the right state until I get to the point where I
      > > build a circuit to start using them.
      > >
      > > I'll usually build it up on a small solderless breadboard, and keep it
      > > on hand. Then, when I start building up an actual computer circuit I
      > > have a quick visual reference to use to make sure I'm going to the
      > > correct pins, I'm holding things in the right state, and so on.
      > >
      > > Plus, if kids come by to see your lab you have something you can
      > > switch on for some quickie blinkenlights. =)
      > >
      > > Mark Graybill
      > > -----------------------------------------------------------------------------------------------------------------
      > > http://saundby.com/
      > > Electronics, Books, Video Games, etc.
      > >
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