QBasic Tutorial 26 - Screen Coordinates - QB64



Screen 13 will be used within this tutorial. Screen 13 has a resolution of 320 x 200. This tutorial will show the screen coofinates.

The tutorial in the old QBasic Tutorial Series, regarding coordinates, was wrong. The old tutorial had screen coordinates of:

(0, 0)
(0, 200)
(320, 200)
(320, 0)

Since the starting coordinate is 0,0 that means that the math equation of n - 1 needs to be used. So, the farthest coordinate for Screen 13 is (320 - 1, 200 - 1) which gives us (319, 199).

The correct coordinates for each corner, of Screen 13, is:

(0, 0)
(0, 199)
(319, 199)
(319, 0)

PSET will place a pixel at a specified coordinate and color.

Code Download 
QBT26_1.BAS - Incorrect Coordinates
QBT26_2.BAS - Correct Coordinates 




QBasic / QB64 Links



QB64 is a free download at www.qb64.org

QB64 Wiki & Manual is found at www.qb64.org/wiki/Main_Page

QBasic 1.1 is found within OldDOS.exe.
OldDos is a free download at download.microsoft.com/download/win95upg/tool_s/1.0/W95/EN-US/olddos.exe

On some web browsers, the Microsoft link does not work, because the download comes as an exe file. A zip file of OldDOS can be found at www.pcxt-micro.com/download.html

QBasic 1.1 needs DOSBox to run on Windows Vista and greater, Mac, and Linux.
DosBox is a free download at www.dosbox.com

Free QB64/QBasic Code 

QBasic.Net - www.qbasic.net

Pete's QBasic Site - www.petesqbsite.com/index.php

QB45 - qb45.org

Phatcode - games.phatcode.net