apple-pascal-1.3-manual

ModeAction0 Fills area of screen with black1 NOR array with screen [NOT (A OR S)J2 AND array with screen complement [A AND NOT SJ3 Complements area of screen [NOT SJ4 AND screen with array complement [S AND NOT AJ5 Copies complement of array to screen [NOT AJ6 XOR array with screen [A XOR SJ7 NAND array with screen [NOT (A AND S)J8 AND array with screen [A AND SJ9 EQUIVALENCE of array with screen [A = SJ10 Copies array to screen [AJ11 OR array with screen complement [A OR NOT SJ12 Screen replaces screen [SJ13 OR screen with array complement [S OR NOT AJ14 OR array with screen [A OR SJ15 Fills area of screen with whiteThe demonstration program GRAFDEMO.TEXT, on APPLE3:, containsmany examples of how to use the Turtlegraphics routines. In particular,procedures such as BUTTERl give strings to procedure STUFF, whichconverts them to a packed array of boolean named BUTTER. ProcedureFLUTTER uses DRA WBLOCK to display the array BUTTER on the screen.A Note About SOURCE: Actually, the SOURCE parameter can be anytype except a file type; DRA WBLOCK really deals with an array of bits inmemory that begins at the address of SOURCE and whose size andorganization depend on the other parameters. For example, the followingstatement uses a single boolean variable, DOT, instead of an array. Itcomplements the screen image at point X, Y:DRAWBLOCK CDOT, 1, l/J, '1J, 1 1, X, Y, 3)However, for most programs the most convenient way to useDRA WBLOCK is with a two-dimensional packed array of boolean, asdescribed above.DRAWBLOCKIII-205