williams-et-al-1983-apple-ii-computer-graphics

CHAPTER 12-BYTE-MOVE SHAPES 1431BYTE #2VERSION # 02• • r • •• • •• •• • •• • • •• • • • •3456• • • • • • •• • • • • • •• • • • • • •• • • • • • •Figure 12-3.If you take the time to calculate the values needed to produce the sevenversions, you should arrive at:BYTE #1 BYTE #2DEC DOT DOT DECVALUE PATTERN PATTERN VALUE------------------------------ ---- -----126 -XXXXXX X------ 1124 --XXXXX XX----- 3121£l ---XXXX XXX---- 7112 ----XXX XXXX--- 1596 -----XX XXXXX-- 3164 ------X XXXXXX- 63Ill ------- xxxxxxx 127What you have in this example is a two-byte animation. Even though thefigure appears to be only one byte wide, in six of the seven possibleplacements, it requires two bytes to represent the line. You should considereach of the bytes in a figure to have its own set of seven separations. ·It is another characteristic of byte-move that any figure requires sevenseparations for horizontal movement and, fu rther, that each figure takesone byte more than you would expect.The line which fits in one byte actually requires a two-byte definition. Afour-byte figure will require five bytes for all the separations. The onlyexception is a figure one dot wide, where all seven versions will fit intoone byte.You can manually move the line from BASIC by typingHGR