We derive the expressions for ψ-functions and generic solutions of
lattice principal chiral equations, lattice KP hierarchy and hierarchy
including lattice N-wave type equations. τ-function of n free fermions
plays fundamental role in this context. Miwa's coordinates in our case appear
as the lattice parameters.Comment: The text of the talk at NEEDS-93 conference, Gallipoli, Italy,
September-93, LaTeX, 8 pages. Several typos and minor errors are correcte