INT 15,87 - Move Block to/from Extended Memory

AH = 87h

CX = word count of block to be moved

ES:SI = pointer to Global Descriptor Table (~GDT~)

on return:

CF = 0 if successful (AH contains return code)

= 1 if error detected

AH = 0 operation successful (ZF also set)

= 1 RAM parity error (if CF set)

= 2 other exception (if CF set)

= 3 gate address on line 20h failed (if CF set)

= 80h on PC and PCjr (if CF set)

= 86h on XT and newer 808x machines (if CF set)

- transfers data blocks to and from extended memory on 80286

and 80386 machines by switching from real to protected mode

for the duration of the transfer

- all real mode interrupts are disabled

- processor shuts down during the switch from protected mode

to real mode on 286 processors