Microsoft KB Archive/42660

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QuickBasic Updates Screen Faster than CGA Can Update

Article ID: 42660

Article Last Modified on 8/16/2005


  • Microsoft QuickBasic 4.0
  • Microsoft QuickBASIC 4.0b
  • Microsoft QuickBasic 4.5 for MS-DOS
  • Microsoft BASIC Compiler 6.0
  • Microsoft BASIC Compiler 6.0b

This article was previously published under Q42660


Below is an example of a basic program that attempts to print data on a screen. Most video systems are fast enough that all of the information can be printed to the screen. The Color Graphics Adapter (CGA) system, however, does not update the screen frequently enough for all lines to be scrolled up. This results in less than 25 lines of text being displayed on the screen while the program is printing. The entire 25 lines will appear on the screen at the end of the loop. Because this is caused by printing to the screen too fast, if this presents a problem for some specific application, put a delay loop inside of the print loop to slow down the print process.

This problem did not occur with earlier versions of QuickBasic.

Code Example

COLOR 11, 1, 1
d$ = STRING$(80, 65)
FOR d% = 1 TO 1000
  PRINT d$

Additional query words: QuickBas BasicCom

Keywords: KB42660