I'm trying to get my Dosbox-based VGA BIOS (which runs from a ROM in UniPCemu, with calls into the emulator itself using the special 0xFE /7 instruction)) running with the Turbo XT BIOS, but strange things are happening.

When it gets to the point of displaying that it has a parallel port, it strangely starts writing to the wrong display page(page 5) instead of the normal page 0 used until that point. Also, someplace further down the road, when it reaches the memory checking process, it simply starts printing the values after each other at the wrong row, instead of keeping the same location at the correct spot.

Internal BIOS main function calls: https://bitbucket.org/superfury/unipcemu/src/ … t10.c?at=master
Internal BIOS ROM generation: https://bitbucket.org/superfury/unipcemu/src/ … ont.c?at=master
Video mode setup: https://bitbucket.org/superfury/unipcemu/src/ … ode.c?at=master
Text mode data: https://bitbucket.org/superfury/unipcemu/src/ … ata.c?at=master
Video Parameter Table: https://bitbucket.org/superfury/unipcemu/src/ … ble.c?at=master

Anyone can see what's going wrong? Why does it start using the wrong video page (page 5, later 7)? The source code of the BIOS (v3.0 just came out 😀 ) can be found at the author's website: http://www.phatcode.net/downloads.php?id=101