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Re: [midatlanticretro] Altair 680 Project Update

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  • Dan
    Well, it seems very odd that with the same rev1-6X motherboard that MITS would use two different IC s. I checked your pics of the motherboard and its the same
    Message 1 of 48 , Mar 2, 2007
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      Well, it seems very odd that with the same rev1-6X motherboard that MITS
      would use two different IC's. I checked your pics of the motherboard and
      its the same as mine. I also have the round toggle switches on mine.
      Have you check the Assembly doc PDF's I posted online to compare ?

      All I remember is that the 680 had a front panel with a different color,
      aside from a different rev motherboard too I suppose. I recall seeing a
      pic online somewhere but I don't seem to have that bookmark.

      I posted sheet 2(rt.half) from my schematics showing IC L being a
      74LS74, the pinouts checkout accordingly.
      http://ragooman.home.comcast.net/computers_altair680.html

      =Dan

      [ My Corner of Cyberspace http://ragooman.home.comcast.net/ ]



      B. Degnan wrote:
      >
      > Dan, Bob, Brian (and anyone who cares :-))
      >
      > The 74L123 is listed in the schematic, I received assistance from
      > Steve Shepard of AltairManuals.com.
      >
      > I have a 1-6X motherboard too. I thought that because the system has
      > the round toggle switches that it was the "680" and that the flat
      > toggle switch version was the "680b", but I don't believe it works
      > that way...ANyone know for sure how to distinguish between the two?
      >
      > I plan to use a terminal, so I don't need the extra Baudot circuitry.
      > Being optimistic, I hope that this computer is simply missing the
      > 74L123, and that the circuity is otherwise intact for a 1200 baud 2
      > stop-bit terminal. I plan to check the I/O circuitry with a
      > magnifying glass just in case.
      >
      > I plan to contact _http://www.mel.wisc.edu/_
      > <http://www.mel.wisc.edu/> for the chip. I may have one on another
      > system I can borrow, I have not found one yet in the easy to find
      > areas of my inventory of chips.
      >
      > Bill
      >
      > At 08:49 AM 3/2/2007 -0500, you wrote:
      >
      >> Hey man, I don't know which documentation you guys are reading,
      >> I suspected you had downloaded the 680b docs already.
      >> How can the 74LS74 can be mistaken for a 74L123.at location L ?
      >> Maybe thats on the 8800--I don't have that manual
      >> I've been checking my original docs with all my notes from when I built
      >> this back then.
      >> My schematics are dated 5/4/76, rev 1-6X mainboard
      >> I have a 680b too, which is what you have as best as I can tell.
      >> I double checked my assembly docs and parts list too.
      >> It also states the 74LS74 is only needed if you use a Baudot terminal.
      >> I suppose your using a standard RS232 terminal,right ?
      >> There's 3 different sets of parts for the I/O configuration.
      >> It's on pg.16,29,30 of the assembly manual.
      >> I scanned it in case nobody has it.
      >> http://ragooman.home.comcast.net/computers_altair680.html
      >> <http://ragooman.home.comcast.net/computers_altair680.html>
      >>
      >> =Dan
      >
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    • Evan Koblentz
      DG Eclipse S/140 from a couple of months ago, now on display in our museum, next to Perkin-Elmer 3120.
      Message 48 of 48 , Mar 20, 2011
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        DG Eclipse S/140 from a couple of months ago, now on display in our museum, next to Perkin-Elmer 3120.
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