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Re: [midatlanticretro] Altair 680 Project Update

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  • B. Degnan
    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
    Message 1 of 48 , Mar 2, 2007
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      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/ 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

      =Dan
    • 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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