KnowledgeBase Archive

An Archive of Early Microsoft KnowledgeBase Articles

View on GitHub

Q43335: cegal() Function in EGA.LIB May Not Work Properly

Article: Q43335
Product(s): See article
Version(s): 1.00
Operating System(s): MS-DOS
Keyword(s): ENDUSER | | mspl13_basic
Last Modified: 16-APR-1990

When using cegal() in the EGA.LIB with Function f1, cegal() doesn't
perform correctly. An example is shown below.

Perform the following function in C

   outp(CRTC_INDEX,INDEX);

where CRTC_INDEX is the port address and INDEX is the register.

The mouse will not see the change in the EGA register; therefore, the
above C call may cause the mouse to not perform properly because the
call bypasses the BIOS routines.

The following are two ways to perform this call so that the mouse will
see the change in the EGA register:

1. Use the EGA.LIB (this does not work):

         e1=0xf1;
         e2=0xd;
         e4=0;
         cegal(&e1,&e2,&e3,&e4,&e5);

2. Use the equivalent BIOS call (this works):

         inregs.x.ax=0xf1;
         inregs.x.bx=0xd;
         inregs.x.dx=0;
         int86(0x10,&inregs,&outregs);

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.