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30294RE: [midatlanticretro] More info on the latest TV prop deal -- show identified!

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  • Kelly D. Leavitt
    Apr 24, 2013
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      From: midatlanticretro@yahoogroups.com on behalf of Wesley Furr
      > Really? Never heard of such a thing! That alone doesn't bode well in
      > my mind... Unless of course there actually was at some point in
      > history a machine that could be physically damaged by code alone...
      > in which case, I sit corrected.
      The TRS-80 model II had a built in HCF in its video system. If you set the sync way out of range it would actually burn things.

      From an old comp.sys.tandy post:
      Mark McDougall" <ma...@...> wrote in message
      news:45639840$0$1581$5a62ac22@......

      > Frank Durda IV wrote:
      >
      > > There were a few sound reasons
      > > behind this, because it was completely possible to program a Model II
      > > to burn up its video system (complete with smoke and sometimes
      > > flames), and a few other expensive hardware pieces were also
      > > vulnerable to being destroyed due to not knowing what you were doing or
      > > if you only programmed half the settings in the alloted time or
      > > similar issues.
      >
      > Wow, that's incredible, and one could argue, incredibly bad design.
      > Having said that, it's entirely possible to destroy your VGA monitor in
      > software too.
      The problem with the video was the monitor driver board. If a sync was
      way out of range, it could cause one of the drivers to just 'turn on solid',
      which exceeded power disapation specs. The problem with this was
      that not only did the part fail, it usually shorted such that it fed 12v
      back
      through the driver circuit. A lot of times it would get far enough to
      get all the way back to the video/keyboard card.

      Kelly
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