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The MASM Forum Archive 2004 to 2012

Miscellaneous Forums => 16 bit DOS Programming => Topic started by: xxxx on February 05, 2005, 01:57:01 AM

Title: video mode
Post by: xxxx on February 05, 2005, 01:57:01 AM
                                                                        MOV AH,00
                                                                         MOV AL,06
                                                                         INT 10H



when i execute a program that contains that instructions the screen goes blank.what's the problem?i'm guessing that the monitor dosen't support it
                                                                         
Title: Re: video mode
Post by: thomasantony on February 05, 2005, 05:08:17 AM
AFAIK,  The screen gets cleared when you set a new video mode

Thomas Antony :U
Title: Re: video mode
Post by: MichaelW on February 05, 2005, 06:11:48 AM
Bit 7 of the mode value controls whether or not the display memory is erased at mode set. If bit 7 is set (e.g. 86h for mode 6) then the display memory is not erased.  But if you are changing from an alphanumeric mode to a graphics mode then you probably should erase the display memory because the alphanumeric modes use the bit planes to store characters, attributes, and font bit patterns, and this data would appear as garbage in the graphics modes.
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