KnowledgeBase Archive

An Archive of Early Microsoft KnowledgeBase Articles

View on GitHub

Q50896: If WIDTH 80,60 in SCREEN 12 Then PALETTE Can Give Wrong Color

Article: Q50896
Product(s): See article
Version(s): 4.50
Operating System(s): MS-DOS
Keyword(s): ENDUSER | buglist4.50 B_BasicCom | mspl13_basic
Last Modified: 21-SEP-1990

In SCREEN 12, if the WIDTH 80, 60 statement is used to set the screen
to 60-line mode and then the PALETTE statement is used to set
attributes and colors, the palette can give erroneous colors. The
problem can be worked around by changing the WIDTH statement to
WIDTH , 30 to set the screen to 30-line mode instead of 60.

The code fragment given below demonstrates the problem in QuickBASIC
version 4.50. The same code fragment runs correctly in QuickBASIC
versions 4.00 and 4.00b.

Microsoft has confirmed this to be a problem in QuickBASIC version
4.50 and in Microsoft BASIC Professional Development System (PDS)
version 7.00 (buglist7.00). This problem was corrected in BASIC PDS
version 7.10 (fixlist7.10).

The program below reproduces the problem on SCREEN 12, which requires
a VGA. It should produce bands of shades of gray going from black to
white across the screen. Instead, it produces bands of the same set of
incorrect colors each time it is run.

   SCREEN 12
   WIDTH 80, 60            'WIDTH 80, 30 gives correct results
   FOR X = 4 TO 60 STEP 4
       A& = 65536 * X + 256 * X + X
       B = X / 4
       PALETTE B, A&
   NEXT
   FOR X = 1 TO 16
       LINE (X * 10, 0)-(X * 10 + 20, 350), X, BF
   NEXT

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT SHALL MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY DAMAGES WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL, CONSEQUENTIAL, LOSS OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF MICROSOFT CORPORATION OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. SOME STATES DO NOT ALLOW THE EXCLUSION OR LIMITATION OF LIABILITY FOR CONSEQUENTIAL OR INCIDENTAL DAMAGES SO THE FOREGOING LIMITATION MAY NOT APPLY.