Gameduino
  James Bowman
  SVFIG March 2011

Arduino as a platform/arduino
  Sketch
  Physical shield spec
  8 Mbit/s SPI bus
  100,000 sold
  Established ecosystem

Genesis of Gameduino
  FPGA sprite code for Forth Day 2010
  Nothing comparable
  Fairly low-cost FPGAs from Xilinx

Hardware/pcb
  Xilinx XC3S200A: 3.3V, SPI flash
  Video is 3 bits per channel, VGA
  Audio is 1 bit for L/R, PWM

Video system/video
  Background characters (10K)
  256 foreground sprites (20K)
  composite buffer (2K)
  collision detection

Audio system/audio
  Low pass filter
  DC term register
  64 sine wave generators, summed
  frequency based
  Started as bleeps, is now more

Under the covers
  SPI interface
  RAMs are working hard! 500 MByte/s
  and... coprocessor

J1/wireframe
  code space 2048 bits distributed RAM
  can write anywhere
  shares memory interface with SPI
  50 MIPS, * 1 cycle, c@ and c! 2 cycle
  Cross compiled in gforth

Random noise/snow
  begin
      RANDOM c@ over c!
      1-
      h# 1FFF and
  again

Raster chasing/raster
  begin
      YLINE c@
      d# 2 * h# 3000 + @
      BG_COLOR !
  again

End/gd128