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Selected Live Demos from "Graphics for the IBM PC" |
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Selected Live Demos from Graphics for the IBM PC
All of the machine demos below are halted by default. Click the machine's Run button to start it running.
From Page 46:
A KALEIDOSCOPE PROGRAM
Let's run a program that will show you some of what BASIC can do on the IBM PC. This program produces a changing kaleidoscope display and is shown in Listing 2-3. Type it precisely as shown. If you make any mistakes, use the editing capabilities of BASIC discussed above to make corrections. Remember to type NEW to clear any previous programs out of memory before typing the new program. Enter RUN to execute the program, noting the wide range of colors available on the IBM PC. A typical display is shown in Fig. 4 in the color photograph section. Note that good effects can be produced with only a few program lines thanks to the power of Advanced BASIC.
{% include machine.html id="xt-cga-256k-1" %}
From Page 58:
Medium-Resolution Color Selection
Every color available on the PC can be displayed in medium-resolution graphics mode, but, unfortunately, only in certain combinations. The background color (that is, the color to which the screen and border default and which graphics are typically set against) can be any of the 16 colors available on the PC, as shown in Table 4-1 The other three colors available at any one time consist of one of two sets. The sets are called palettes because, like painters' palettes, each is a group of colors from which the PC artist may choose to work.
Palette number 0 contains green, red, and brown, which are colors 1,2, and 3, respectively (Table 4-2). (Many monitors will display yellow rather than brown.) These colors look excellent on an RGB monitor (see Fig. 5A in the color photograph section), but, unfortunately, often tend to look rather muddy on a television.
Palette number 1 contains cyan, magenta, and white, which are, respectively, colors 1, 2, and 3 (Table 4-2). Cyan is a light blue, and magenta is a light red. These colors aren't as vivid on an RGB monitor as those in the other palette (See Fig. 5B in the color photograph section), and can look somewhat washed out if screen brightness is high. However, the colors in palette 1 look just about as good on a television as on an RGB monitor, and because white appears much sharper on a television than any other color, this palette is the palette of choice for television work. (The same is true of any composite monitor.)
{% include machine.html id="xt-cga-256k-2" %}