BASIC-DOS

BASIC-DOS Screen Commands

Screen commands include:

• CLS
• COLOR
• ECHO
• LOCATE
• PRINT
• SCREEN
• WIDTH

Each session has its own console, which may occupy only part of the screen (see Sessions). Screen commands operate on the current session’s console, and coordinates are relative to the console, not the screen.

When a BAS program ends (or is aborted), the video mode it started with is restored, undoing any SCREEN or WIDTH changes, and the console’s original size and border are restored as well.

CLS

CLS

Clears the console using the background color and moves the cursor to the top left corner.

COLOR

COLOR [foreground][,[background][,border]]

Sets the foreground (0-15), background (0-15), and border (0-255) colors of the console. For blinking colors, use 16-31 for foreground, 8-15 for background, and 128-255 for border. Omitted values are unchanged (eg, COLOR ,1).

In SCREEN 1, the values are the background color (0-15) and palette (0 or 1) instead.

The colors are:

ECHO

ECHO [ON

OFF]

Controls the echo of lines in a BAT file. BAT files echo each line before running it, unless ECHO OFF is used; a line beginning with @ is never echoed (eg, @ECHO OFF). Echoed lines are displayed with a @ in front (eg, @REM Starting), where PC DOS would display a prompt. ECHO without ON or OFF displays the current setting.

Every BAT file run from the prompt starts with ECHO ON, and the setting remains in effect when one BAT file runs another. BAS files never echo their lines. A @ at the start of a command typed at the prompt is ignored, as in later versions of PC DOS.

LOCATE

LOCATE [row][,[col][,cursor]]

Moves the cursor to the specified row and col (starting at 1,1), and hides (0) or shows (1) the cursor. The cursor remains hidden until the next input. Omitted values are unchanged.

PRINT

PRINT [expression][;

,][expression]…

Prints a series of values, separated by semicolons or commas. A semicolon prints the next value immediately after the previous one, and a comma prints a tab. Numbers are printed with a leading space (or minus sign) and a trailing space. If the list ends with a semicolon or comma, the cursor remains on the same line; otherwise, PRINT moves to the next line.

PRINT "A"; 1; "B", 2
A 1 B	 2

Comma print zones aren’t supported yet (commas currently print a tab), and neither is PRINT USING.

SCREEN

SCREEN [mode][,burst]

Sets the screen mode on a color adapter:

• 0: text
• 1: 320x200 graphics (4 colors)
• 2: 640x200 graphics (2 colors)

A burst of 0 disables color in mode 0, and a burst of 1 disables color in mode 1. Changing the mode clears the screen and removes the console’s border, if any, so the console occupies the entire screen. Text output (eg, PRINT) works in all modes.

WIDTH

WIDTH 40

80

Sets the number of columns in text mode (which clears the screen). In SCREEN 1, WIDTH 80 selects SCREEN 2, and in SCREEN 2, WIDTH 40 selects SCREEN 1.

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