Page:Calligraphy for computers (Hershey, 1967) (IA DTIC AD0662398).djvu/29

 $ \begin{align} \left ( \Delta X, \Delta Y \right ) \left ( 2, 0 \right ), & \left ( 2, 1 \right ) \\ \left ( \Delta X, \Delta Y \right ) \left ( 1, 0 \right ), & \left ( 2, 1 \right ) \\ \left ( \Delta X, \Delta Y \right ) \left ( 1, 1 \right ), & \left ( 2, 1 \right ) \end{align} $

or by permutations or reversals among these. Jogs in the lines become perceptible when more elaborate patterns are used. The linear characters A, K, M, N, V, W, X, Y, Z contain a variety of inclined lines and limitations on the possible inclinations determine the shapes of the characters. The Roman style of character is available to a dot plotter, but the inclinations for an Italic style of character would be too exaggerated.

Dot plotting on NORC is accomplished by either of two character plotting routines. Block No. 0130 gives a mathematical repertory while Block No. 0160 gives a cartographic repertory. These NORC subroutines have been converted recently to FORTRAN IV by the Control Data Corporation.

The digital data for each character are packed in the data array of each subroutine. The data consist of decimal digit pairs. The first digit pair gives the half width of the character. The second digit pair gives the X-displacement and the third digit pair gives the Y-displacement to the first dot. The subsequent digit pairs give displacements to successive dots. In each of these digit pairs the first digit is the X-displacement and the second digit is the Y-displacement. Negative displacements are expressed by 9's complements. Whenever the first digit is 5, the previous displacement is repeated a number of times equal to the second digit. If the digit pair is 00, the next four digits are interpreted in the same way as the second and third digit pairs, except that displacements are relative to the last plotted dot. The digit pair 50 signifies the end of character. 23