Format of task switcher version structure:
Offset	Size	Description	)
 00h	WORD	major version of supported protocol  (current protocol is 1.0)
 02h	WORD	minor version of supported protocol
 04h	WORD	major version of task switcher
 06h	WORD	minor version of task switcher
 08h	WORD	task switcher ID (see AX=4B03h)
 0Ah	WORD	operation flags
		bit 0: set if task switcher disabled
		bits 1-15: reserved (0)
 0Ch	DWORD	pointer to ASCIZ task switcher name
		("MS-DOS Shell Task Switcher" for DOSSHELL task switcher)
 10h	DWORD	pointer to previous task switcher's entry point or 0000h:0000h