Turbo Basic

GraphicsWhen it comes to displaying information on the screen, a program generated byTurbo Basic must work within the constraints of the display hardware available toit. Turbo Basic supports three main class~s of video interfaces on PCs and compatibles:the Monochrome Display Adapter, which is only capable of monochrometext, and the Color/Graphics Adapter (CGA) and the Enhanced GraphicsAdapter (EGA), both of which can produce text and graphics in color and in blackand white (see Table 4-5).AdapterMonochromeTable 4-5Screen ModeoCGA 0,1,2EGA 0, 1, 2, 7, 8, 9, 10CGA = Color/Graphics AdapterEGA = Enhanced Graphics AdapterGraphics Adapter CharacteristicsText Format80 column40/80 col.40/80 col.Comments80 x 25 characters, with 4attributes (normal, highlight,blinking, underline)Up to 16 colors (in text modeonly); up to 4 colors ingraphics mode. Screen resolution:640 x 200 pixels.Screen resolution: up to 640X 350 pixels. Up to 16 colorsout of a 64-color palette(depending on EGA memory)Corresponding to the talents of these video boards, Turbo Basic can select any ofthe supported text or graphics modes with the SCREEN and/or WIDTH statements.The Text ModesIn 80 column text mode (the only mode available with the Monochrome DisplayAdapter), the screen consists of 25 lines of 80 character positions each, numbered 1to 25 (top to bottom) and 1 to 80 (left to right). (See Figure 4-2.) In 40 column textmode (available with the CGA/EGA adapters), the screen consists of 25 lines of 40characters. Each position on each line can contain any of the characters listed inthe character set chart in Appendix F.110 Turbo Basic Owner's Handbook