INT 2F - AVATAR.SYS v0.11+ - GET DATA SEGMENT
        AX = 1A44h
        BX = 4156h ('AV')
Return: AX = 0000h
        DS = data segment
        CX = size of data segment
Note:   AVATAR.SYS calls this function whenever it is invoked.  If each
          process under a multitasker hooks this function and provides a
          separate data segment, AVATAR.SYS becomes fully reentrant.
SeeAlso: AX=1A3Fh