1.1 --- a/ula.py	Sun Dec 18 18:59:08 2011 +0100
     1.2 +++ b/ula.py	Sun Dec 18 19:19:11 2011 +0100
     1.3 @@ -4,6 +4,9 @@
     1.4  Acorn Electron ULA simulation.
     1.5  """
     1.6  
     1.7 +from array import array
     1.8 +from itertools import repeat
     1.9 +
    1.10  LINES_PER_ROW = 8       # the number of pixel lines per character row
    1.11  MAX_HEIGHT = 256        # the height of the screen in pixels
    1.12  MAX_SCANLINE = 312      # the number of scanlines in each frame
    1.13 @@ -13,6 +16,8 @@
    1.14  MAX_MEMORY = 0x10000    # the number of addressable memory locations
    1.15  BLANK = (0, 0, 0)
    1.16  
    1.17 +screen = array("B", repeat(0, MAX_WIDTH * 3 * MAX_HEIGHT))
    1.18 +
    1.19  def update(ula):
    1.20  
    1.21      """
    1.22 @@ -21,24 +26,22 @@
    1.23      ULA.
    1.24      """
    1.25  
    1.26 -    screen = []
    1.27 -
    1.28      ula.vsync()
    1.29 +    pos = 0
    1.30      y = 0
    1.31      while y < MAX_SCANLINE:
    1.32 -        row = []
    1.33          x = 0
    1.34          while x < MAX_SCANPOS:
    1.35              colour = ula.get_pixel_colour()
    1.36              if x < MAX_WIDTH and y < MAX_HEIGHT:
    1.37 -                row.append(colour)
    1.38 +                screen[pos] = colour[0]; pos += 1
    1.39 +                screen[pos] = colour[1]; pos += 1
    1.40 +                screen[pos] = colour[2]; pos += 1
    1.41              x += 1
    1.42          ula.hsync()
    1.43 -        if y < MAX_HEIGHT:
    1.44 -            screen.append(row)
    1.45          y += 1
    1.46  
    1.47 -    return screen
    1.48 +    return screen.tolist()
    1.49  
    1.50  class ULA:
    1.51