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33Re: Space Invaders

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  • herc_fun
    Mar 5, 2002
      --- In cosmacelf@y..., Dave Ruske <dave@r...> wrote:
      > Sounds like a nice piece of work, Charlie! I presume you were using
      the 1861
      > for graphics?
      > TinyELF (the emulator for the Palm OS) could probably run the code,
      depending ......
      > Bill Richman's emulator (the one I think you refer to) may run the
      code, but ......
      > By the way, let me know if you'd like to make your Space Invaders
      > available to others....
      > Dave

      The game ran on the original Netronics ELF II with a 4k memory
      expansion card. I made my own joystick which "piggy backed" on the
      hex keypad and input button lines I believe so the game could be
      played without the custom joystick. It used every available cycle;
      in fact it wouldn't even display the score unless there were enough
      cycles left over to convert the score to decimal and display it.
      Speaking of score, I used the 8bit output port on the memory
      expansion card to hook up another 2 seven-segment displays to give a
      total of 4 hex-digit display.

      It would be interesting to know of this code running again; whether
      on classic hardware or an emulator. To that end, I am forwarding
      Dave a zipped assembly listing of the code and a binary memory image
      for posting on his cosmacelf.com site. I'll monitor this discussion
      group and attempt to answer questions if anyone undertakes reviving
      this program. By the way, the first question regarding the program
      may be "why is there a long branch to 0xF000 at the start of the
      code?"; That is where the ROM monitor program lived on ELF II which
      let you read/write casette tape, display/alter memory and start
      program execution at location 0x0003.

      If there is interest in this one, I'm willing to post my LIFE program
      and ELFIGOL (ELF Interpretive Game Oriented Language).
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