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Re: [cosmacelf] Space Invaders

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  • Dave Ruske
    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,
    Message 1 of 5 , Mar 2, 2002
      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
      on what you used for game control. One shortcut I took in TinyELF was the use
      of regular button objects for the hex keypad --- and the side effect is that
      while one of those buttons is pressed, 1802 code execution is effectively
      paused while the Palm OS sits and spins. I did something special for the
      Input key (programmed it using a gadget) so that one doesn't exhibit that
      behavior. I keep meaning to get back to TinyELF's code to add some features
      (such as a sorely-needed program import), but as priorities go that project
      usually gets trumped.

      The other, more obvious, problem with TinyELF is that it *crawls*. You'd
      think that emulating a 1.79 MHz 8-bit machine on a 20+ MHz Dragonball would
      be quicker, but in practice the code needs to do a lot of cycle counting to
      properly emulate the Pixie graphics. When Palm comes out with their 200 MHz
      ARM handhelds, I think TinyELF may be able to approach the speed of a real
      ELF.

      Bill Richman's emulator (the one I think you refer to) may run the code, but
      it depends... last time I played with it, the STXD instruction didn't work,
      and I don't believe that emulator has been updated. As I recall, the
      instruction did the store-via-X but didn't decrement afterwards. If you're
      using X as a stack pointer while running a virtual 1861, there's no easy fix
      for this. Adding a decrement alone wouldn't work, because an interrupt could
      hit between the STX and the DEC and nail the stack.

      By the way, let me know if you'd like to make your Space Invaders game
      available to others. I've just recently created a software area on
      cosmacelf.com, and I'd welcome any such contributions.

      Dave

      On Saturday 02 March 2002 08:30 pm, you wrote:
      > Hi group, I'm a newbie here. I have an awesome Space Invaders game
      > that I wrote about 20 years ago for the ELF II. Full graphics and
      > gameroom action and all. It even makes Q click when you hit suff! (If
      > you were one of those folks who pu a speaker on Q). I still have
      > machine readable source code for it (actually the code exists on a
      > mainframe where my 1802 cross-assembler lives). I want to run this
      > code again but my actual ELF hardware is somewhat less than operative.
      > What's the status of emulators for ELF II? (I know there is the
      > original ELF emulator complete with toggles but is needs the 4k
      > expansion card etc...) Anyone got an interest in this?
    • herc_fun
      ... the 1861 ... depending ...... ... code, but ...... ... game ... The game ran on the original Netronics ELF II with a 4k memory expansion card. I made my
      Message 2 of 5 , 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
        game
        > 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).
      • druske
        I ve posted the text and binary versions of Charlie Brint s Space Invaders game to the software archive on cosmacelf.com. It s likely to be some time before I
        Message 3 of 5 , Mar 5, 2002
          I've posted the text and binary versions of Charlie Brint's Space
          Invaders game to the software archive on cosmacelf.com. It's
          likely to be some time before I get a chance to give it a whirl
          myself, but if someone else gets it running (or has troubles) please
          let us know!

          Dave
        • jdrose_8_bit
          That is cool. I knew about Mr. Robson s Invaders for the Studio II. Did not know there was one for the Elf II. I found this one in the files section:
          Message 4 of 5 , Mar 8, 2013
            That is cool. I knew about Mr. Robson's Invaders for the Studio II. Did not know there was one for the Elf II.

            I found this one in the files section:
            http://groups.yahoo.com/group/cosmacelf/files/Elf%20II/

            Is this one yours?


            >
            > Hi group, I'm a newbie here. I have an awesome Space Invaders game
            > that I wrote about 20 years ago for the ELF II. Full graphics and
            > gameroom action and all. It even makes Q click when you hit suff! (If
            > you were one of those folks who pu a speaker on Q). I still have
            > machine readable source code for it (actually the code exists on a
            > mainframe where my 1802 cross-assembler lives). I want to run this
            > code again but my actual ELF hardware is somewhat less than operative.
            > What's the status of emulators for ELF II? (I know there is the
            > original ELF emulator complete with toggles but is needs the 4k
            > expansion card etc...) Anyone got an interest in this?
            >
            > Old but sill 8bit at heart.
            > Charlie
            >
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