Width sets up the numbest- of pixels that will make up the width of the new screen. There is no problem in opening a screen that is wider than the physical limit of the television or monitor display, and extra-wide screens can be manipulated by the SCREEN OFFSET command. The widest possible screen is 1024 pixels across, from zero to 1023.
Height holds the number of pixels that make up the height of the screen. Like the width parameter, this can be larger than the visible screen height to a maximum of 1023 pixels, and scrolled into view. Screens with oversized widths and heights can be used with all of the normal screen techniques which are explained later.
Colours sets the number of colours to be used for the new screen. The choice for this number is normally between 2,4,8,16 or 32. There are two special sorts of screens that can make use of 64 colours (Extra Half Bright mode screens), and 4096 colours (Hold And Modify mode screens), and these modes are explained at the end of this Chapter.
Pixel mode is a choice of the width of the pixel points on the screen. Lowres is the normal status, allowing 320 pixels to be displayed across the screen, at any one time. Hires halves the width of each pixel, and so allows 640 to be displayed.
LOWRES
function: set screen mode to 320 pixels wide
Screen Open number,width,height,colours,Lowres
HIRES
function: set screen mode to 640 pixels wide
Screen Open number,width,height,colours,Hires
When the default screen is automatically opened, screen 0 is the equivalent to the following setting:
X> Screen Open 0,320,200,16,Lowres
To open screen number 1 as an oversize high-resolution screen with eight colours, you would use something like this:
D> Screen Open 1,600,400,8,Hires
This routine opens all eight available screens and brings them into view:
D> Curs Off : Cls 13: Paper 13
Print : Centre "Hello, I'm SCREEN 0"
For S=1 To 7
Screen Open S,320,20,16,Lowres
Curs Off : Cls S+2 : Paper S+2
Centre "And I am SCREEN"+Str$(S)
Screen Display S,,50+S*25,,8
Next S