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Re: [midatlanticretro] I finally finished my Obtronix Apple 1 reproduction!

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  • Bob Grieb
    Scott,    I did some looking, and found a chip called AM2808C, which you can buy at Anchor Electronics for $2.95 It s a 1Kx8 dynamic shift register in an
    Message 1 of 3 , Jul 14, 2008
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      Scott,

         I did some looking, and found a chip called AM2808C,
      which you can buy at Anchor Electronics for $2.95
      It's a 1Kx8 dynamic shift register in an 8-pin package.
      Uses a two-phase clock just like the Signetics part, and +/-5V.
      The pinout is a little different from the 2504V, but if you
      want to make a little adapter, it looks like it might work.
      I found the data sheet for the AM2808 chip if you want it.

      Bob Grieb

      --- On Sun, 7/13/08, us21090 <us21090@...> wrote:
      From: us21090 <us21090@...>
      Subject: [midatlanticretro] I finally finished my Obtronix Apple 1 reproduction!
      To: midatlanticretro@yahoogroups.com
      Date: Sunday, July 13, 2008, 3:33 PM

      All,

      I finally finished my Obtronix Apple 1 reproduction!

      Actually, building the Apple 1 didn't take much time at all! It was
      the custom work on the mounting board, the curved and angled plastic
      leg brackets and, and ...

      I uploaded photos of it to
      http://www.vintage- computer. com/vcforum/ album.php? u=6611

      I also have a request:

      My Obtronix Apple 1 reproduction had a bad Signetics 2504v. I don't
      think it was DOA (I believe it just "developed" the problem recently).

      The Signetics 2504v is a 1024-bit dynamic shift register, 8-pin dip.
      It's used here to as part of the display control. The problem I saw
      was odd numbers (1,3,5,7,9,A, C,E) in every other screen column were
      displayed as the preceding ASCII character (0,2,4,6,8,@ ,B,D). Data
      from the keyboard was stored correctly in main RAM. The video memory
      problem just displayed it incorrectly.

      Anyway, does anyone have a source of a Signetics 2504v? Or possibly,
      is there other junk-hardware- for-parts that I could pull a 2504v?

      Thanks!
      Scott Austin


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