EXTENDED BASIC 2.8 GRAPHICS ENHANCEMENT MODULE

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The TI-99/4A has a powerful video processor chip that was crippled by XB. Normally only a fraction of its capabilities can be used by an XB program., but Extended BASIC v2.8 G.E.M. provides graphics packages that free the XB programmer from these restrictions. XB 2.8 G.E.M. is a combination of the original XB G.E.M. and Tony Knerr's XB 2.7. Adding 15 banks of ROM made it possible to add many significant enhancements and make a much more powerful package. (XB 2.8 G.E.M. requires the 32k memory expansion.)

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XB256 lets you define 256 characters, more than twice the 112 normally available in XB. There are two independent screens. Screen1 is the normal XB screen. Screen2 lets you define 256 characters, and additionally you can have up to 28 double sized sprites using the Screen1 patterns. You can toggle between the two screens as desired, preserving the graphics in each screen. You can scroll screen characters left, right, up, or down. By specifying a window area you can scroll just the characters in the window. Other routines let you scroll smoothly one pixel at a time to the left, right, up or down, or do a “text crawl” like the title scene of “Star Wars. You can hilight text, play sound lists, print text using 32 columns and much, much more.

T40XB provides easy access to the 40 column text mode. There are two independent screens. G32 is the normal XB 32 column screen. T40 is the 40 column text screen which displays 24 rows of 40 columns.. You can toggle between the two screens as desired, and the graphics on each screen are preserved. When using the T40 screen there are assembly equivalents that replace PRINT, CLEAR, COLOR, INPUT, CHAR, HCHAR, VCHAR plus routines that will scroll the screen and invert text on the screen.

T80XB provides easy access to the 80 column text mode provided by some display devices or Classic99. It is virtually identical to T40XB.

The Missing Link provides easy and versatile access to bit mapped graphics. You can plot points, lines, circles and boxes. Turtle graphics can be used with none of the ink and color restrictions found in LOGO. Up to 32 moving sprites can be placed on the screen. Text can be input from or displayed to the screen. Word wrap is used when displaying text. The character size can be changed, permitting up to 32 rows by 60 columns on the screen. Different sized text can be displayed simultaneously on the same screen.

The Missing Link Graphic Adventure – This version of TML was modified so that bit mapped graphics pictures can be added to text adventures. It can load pictures to the top two thirds of the screen while having text on the lower third. The lower third of the screen will scroll automatically as you input commands to the computer. T

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XB 2.8 G.E.M can run TI BASIC programs that use character sets 15 and 16, usually with a considerable increase in speed.

CALL LOAD(filename) now uses the fast assembly language loader from the minimemory cartridge. This is about 20x faster than the normal loader used by other XB variants. You can now load compressed code, use REFs and most of the other features missing from the normal XB loader.

CALL HELP displays a detailed help menu with brief descriptions of all the new calls in XB2.8. There are tables showing the color codes and character sets. You can look at any of the 60 built in fonts, find the ASCII code for a key and convert numbers in decimal, hexadecimal or binary.

60 fonts are contained in the cartridge roms. A font can be loaded with CALL FONT(number). The graphics packages have CALL LINKs that load a font to be used by the special graphics modes.

RND now uses the same code as the TI BASIC random number generator. This is about 5x faster than the XB random number generator. Unlike all other XB variants, a LOAD program will actually produce random numbers.

There are changes to the line editor. You can enter long XB lines with up to 12 rows of code. The cursor repeat speed is faster. When editing a program line the cursor appears in the usual place, but you can go left and change the line number. You can go up or down a row when editing a program line.

You can customize the screen colors and use any of the 60 fonts. Hold down a key at startup to defeat autoloading from disk 1. Or you can reverse this so you have to hold down a key to force autoload.

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15 new calls have been added to XB 2.8. With these you can:

Load a font from cartridge, and save and load fonts from disk.

Save a program of any size in IV254 format.

RUN a program with a string variable name.

Chain a program from a running program with instant startup and without doing a prescan or resetting any of the variables of the calling program. With this you can have programs much larger than the usual 24K limit in XB.

Change graphics modes as desired from the command line or from a running program and do CALL FILES with the same statement. If a program requires a particular graphics mode you can select that mode in the first line of the program.

And much, much more...