Graphics BASIC is a third-party extension to the Commodore BASIC V2.0 programming language of the Commodore 64 computer. It was originally written in 1983 by Ron Gilbert and Tom McFarlane. The program was licensed to Hesware, which briefly sold the program in 1984 as part of its product line before going out of business. The program was later extended by Ken Rose and Jack Thornton, and repackaged and sold in 1985 by Epyx under the title Programmers BASIC Toolkit. Graphics BASIC adds over 100 new commands to the BASIC language, providing an easy-to-use API to the relatively advanced (at the time) graphics and sound hardware capabilities of the Commodore 64. The only access to these features with Commodore BASIC alone is through the cumbersome use of PEEK and POKE commands. Graphics BASIC was delivered on a single 5.25" floppy disk, containing the language itself and numerous, very simple demo programs showing off the new features of the language. A cartridge version was also available. Features Graphics Graphics BASIC's main feature is its easy-to-use graphics commands, including commands to draw dots, lines, circles, ellipses, rectangles, and polygons. The following gives an example of how the commands were used: DOT 160,100 LINE 80,50 TO 240,150 BOX 10,10 TO 20,20 As can be seen from the above, the syntax is somewhat similar to that of GW-BASIC's or AmigaBASIC's graphics commands, but different enough to prevent source-code compatibility. The Commodore 64 has separate video modes for text and graphics. Switching between these is extremely easy in Graphics BASIC. TEXT switches to text mode, HIRES switches to 320×200 two-colour graphics, and MULTI switches to 160×200 four-colour graphics. Graphics BASIC also allows the screen to be horizontally split between multiple modes. Using all 16 colours is possible in both HiRes and Multi modes, but if two incompatible colours are drawn onto the same 8×8 pixel block, the entire block fills with the colour drawn later. This is due to a technical limitation of the Commodore 64's VIC-II display chip. One of the more unusual choices of syntax in Graphics BASIC was the setting of graphics colours. To set the foreground and background colours of the text mode, you use the commands COLOUR and BACKGROUND, followed by either a number from 0 to 15, or a pre-defined symbolic constant such as WHITE or BLACK. To set the colours of the graphics mode, the command syntax is of