Tag: Darrell Aldrich

by Darrell Aldrich This is a brief description of the use of the color mask byte (Location 81210) for high re solution graphics in Apple Integer Basic. This mask specifies an 8 bit pattern of plottable X coordinates, with the pattern repeating itself every eight coordinates, going from left to right. The bits in this byte represent the colors violet and green, alternately. (See Figure 1). Suppose we want to mask off every other green bar on the screen as…

By Darrell Aldrich While written for Applesoft II, this article is also applicable to Integer Basic HIRES graphics mode. The High Resolution Graphics screen is composed of 280 vertical bars (X coordinates), by 160 units high (Y coordinates). The even-numbered bars are violet in color, while the odd-numbered bars are green. The color white is produced by plotting adjacent green and violet bars. (Green+Violet=White. ) By plotting only on even bars, (even X coordinates), violet plots can be made. However,…