Int 15 Fn 87  - System - Copy Extended Memory                              [B]

   AH = 87h
   CX = number of words to copy (max 8000h)
   ES:SI -> global descriptor table

Return: CF set on error
   CF clear if successful
   AH = status
       00h source copied into destination
       01h parity error
       02h interrupt error
       03h address line 20 gating failed
       80h invalid command (PC,PCjr)
       86h unsupported function (XT,PS30)

Notes: copy is done in protected mode with interrupts disabled by the default
     BIOS handler; many 386 memory managers perform the copy with
     interrupts enabled
   this function is incompatible with the OS/2 compatibility box

See Also: AH=88h,AH=89h

Format of global descriptor table:
Offset Size    Description
 00h 16 BYTEs  zeros
 10h   WORD    source segment length in bytes (2*CX-1 or greater)
 12h  3 BYTEs  24-bit linear source address, low byte first
 15h   BYTE    source segment access rights (93h)
 16h   WORD    zero
 18h   WORD    destination segment length in bytes (2*CX-1 or greater)
 1Ah  3 BYTEs  24-bit linear destination address, low byte first
 1Dh   BYTE    destination segment access rights (93h)
 1Eh 18 BYTEs  zeros