fuz
2020-12-23 00:17:51
The offset of the current video page from the beginning of the regen buffer is recorded in the BDA at 0040:004e. The text mode regen buffer is found at segment b000 for MDA and HGC cards and at b800 for all other cards. Query the equipment byte using int 11h to find if an MDA card is installed.
Refer to this article for further details.
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While you could use
Int 11hthat will only tell you the default display at startup, not necessarily the card the BIOS is currently writing to as the default display. IMHO if you want to know the address of the current text regen buffer the BIOS is actively using then I'd check 0040:0063. If it returns 3B4h then it is Monochrome and thus the current active regen buf segment is at b000h otherwise it is 0b800h. I only mention this if you are trying to figure out the regen buffer that the BIOS routines are currently writing to (It could be a dual head system)