INT D4 - PC-MOS/386 v3.0+ - GET SYSTEM CONTROL BLOCK POINTER
        AH = 02h
Return: AX = 0000h
        ES:BX -> System Control Block in V86 mode (see below)
        ES:EBX -> System Control Block in native mode (see below)
Note:   superseded by AH=26h
SeeAlso: AH=04h,AH=10h,AH=26h,AH=28h,AH=29h,AH=2Ah,INT 21/AX=3000h,INT 38

Format of System Control Block:
Offset  Size    Description
 00h    WORD    pointer to first TCB in chain
 02h 17 BYTEs   reserved
 13h    WORD    pointer to current task's TCB
 15h    WORD    pointer to TCB of visible (console) task

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