Font ungrades revisited; full screen graphics in mode 7+. (Outpost: Atari) Richard Whitsell.
In the July Outpost, John Anderson created a program that changed the Atari default character set into a more pleasant, more readable character set. From that beginning, I developed some improved code that installs the font, making it the default character set at boot time, in AUTORUN.SYS file format. Complete instructions are to be found in the program itself, which appears as Listing 1.
Of course, to make a successful installation you must also have a copy of John's original program. For an introduction to character sets, take a look at the January 1982 Outpost column.
Full Screen Graphics in Mode 7+
Listing 2 is a subrouting utility that will set up a GR.7+ screen and allow you to create a 160 x 192 GR.7+ screen and to plot or draw lines in the entire available screen area.
To plot or draw a line, you must have your X and Y coordinates stored in the variables XP and YP. To plot a point, you then must GOSUB to line 30000. To draw a line, you should GOSUB 31000.
To set up the GR.7+ screen, all 54 values in the DATA statements can be put in a string, or page 6, or wherever else you might like, and called up with a USR statements. The routine will change only a GR.8 screen to GR.7+, so make sure that you issue a GR.8 or GR.8+16 command before invoking the USR call.
Listing 3 is a sample program that creates an interesting full-screen display on the GR.7+ screen. Simply enter this program along with Listing 2, and you are up and running.
I hope you enjoy exploring these programs as much as I enjoyed putting them together for you. For those who want to avoid typing drudgery, the three of them are available for download through Creative Computing Online, via CompuServe (type GO CRE). I first "met" John Anderson there, and find that the Online arm of Creative is at least as exciting as the print version. You can easily get in touch with either of us on CompuServe. My ID is 75056,1527, and John's is 76703,654. Please feel free to send us your comments, improvements, and new ideas. So long now, and catch you online.