An older, 16-bit version of The Art of Assembly Language Programming can be found at http://webster.cs.ucr.edu/. In that text you will find information about the 80x86's 16-bit addressing modes and segmentation. More information about the HLA Standard Library mem.alloc and mem.free functions can be found in the HLA Standard Library reference manual, also on Webster at http://webster.cs.ucr.edu/ or at http://artofasm.com/. Of course, the Intel x86 documentation (found at http://www.intel.com/) provides complete information on 80x86 address modes and machine instruction encoding.