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23682Re: [midatlanticretro] 50 years of Computer Games

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  • Dan Roganti
    Dec 6, 2011
      On 12/06/2011 09:30 PM, Bill Sudbrink wrote:
      > David Gesswein wrote:
      >> Vector without display lists you need to rewrite everything at 30+ Hz
      >> to prevent flicker.
      > I'm thinking a vector display with a display list. The SWTPc SS-30 bus
      > provides a 4 byte interface per slot. I'm thinking a of programming
      > interface something like:

      yes, the display list is necessary to avoid any lag, flicker, etc in the
      display - and offload the processing from the CPU. Much like in a raster
      video display.

      However for the next VCF workshop kit I'm planning, I intend to use an
      onboard 6502 for processing. Mainly for 2 reasons, this saves on parts
      and the firmware will be flexible for future hacks - and open source.
      I'm keeping it a vintage design - after all it's VCF and not Maker Faire
      ;) It's still fast enough when running 2mhz to maintain the screen
      refresh. The 6502 has the lowest instruction cycle count amongst all the
      other 8bitters - just as the 6800 but guess who's popular :)

      So then your host system would run the app software containing the game,
      graphics, etc. While the vector display board will contain all the
      graphics primitives in firmware, but then in vectors. It will save a
      host of hardware when you compare it to something like the Asteroids
      arcade game. And still have enough resolution, 1024x1024, this will
      also use 10bit DAC's as in that arcade - but not the same part# - after
      35yrs, they're still so friggin' expensive ($25). You can get modern
      DAC's that are much cheaper and quality as near as the AD561 used in
      that arcade.

      This kit will have options to connect via a parallel port or memory
      mapped I/O port - which most vintage computers can support. So then it
      can be compatible for most systems using one type of circuit board while
      not needing to make a card for each and every form factor, Apple II,
      S-100, SS-50, etc. It'll be a standalone box that sits beside your
      vector monitor.

      > With relative vertexes (vertices?) moving the ships around the screen
      > will require a fewer operations. Rotations will still be painful.

      Rotations are doing using Matrix Math - it's less painful than in a
      raster graphics, as you only only to worry about the vertices. And you
      use Look Up tables for the Trig functions - to speed up the math. Just
      as they did on the PDP-1 SpaceWar.

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