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#int15

2 posts

FreeDOSDeep Dive October 3, 2026 7 min read

BIOS INT 15h AH=87h: The Protected-Mode Block-Move Service

Understand the AT BIOS block-move descriptor table, 24-bit addresses, transfer limits, status flags, and why XMS or a DPMI host usually owns memory.

#freedos#dos#bios

FreeDOSDeep Dive October 3, 2026 6 min read

Interpret INT 15h AH=88h as a bounded BIOS memory count, check carry and support limits, and keep it separate from E820 and XMS allocation.

#freedos#dos#bios