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New photo - RCA eval board

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  • lonsite
    I ve just uploaded a photo of my RCA CDP18S020 COSMAC eval board, circa 1976. Sorry for the poor quality, but I have a really cheap digital camera :-( The
    Message 1 of 1 , May 8 5:21 PM
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      I've just uploaded a photo of my RCA CDP18S020 COSMAC eval board,
      circa 1976. Sorry for the poor quality, but I have a really cheap
      digital camera :-(

      The board came with a 2.0 MHz CDP1802 CPU, an RCA hex monitor in CMOS
      ROM, two CDP1822 CMOS RAMs (256 X 4 bits each), and LEDs on every CPU
      address and data line. Great for debugging - you can single step
      your program and watch the blinkenlights.

      To this, I added a 6-digit hex display with a 74917 decoder/driver, a
      24-key keyboard, battery backup for the CMOS RAM, and eight 5101 NMOS
      RAMs, for a whopping total of 1,280 bytes of RAM.

      I wrote a hex monitor that uses the keyboard and display, and burned
      it into a 2716 2K X 8 NMOS EPROM. This is instead of the original RCA
      monitor which needed a serial terminal (a big deal in 1976).

      Applications included a music generator (using a speaker on the CPU Q-
      line), real-time clock display (using a 5V 60Hz input on the CPU EF1
      line), and a port of CamelForth (work in progress).

      E-mail me if you want any more details, or just to reminisce.
      -- Harold
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