Duality symmetric massive type II theories in D=8 and D=6

We study T2 compactification of massive type-IIA supergravity in presence of possible Ramond-Ramond (RR) background fluxes. The resulting theory in D=8 is shown to possess full SL(2,R)xSL(2,R) T-duality symmetry similar to the massless case. It is shown that elements of duality symmetry interpolate between massive type IIA compactified on T2 and ordinary type IIA compactified on T2 with RR 2-form flux. We also discuss relationship between M-theory vacua and massive type-IIA vacua. The D8-brane is found to correspond to M-theory 'pure gravity' solution which is a direct product of 7-dimensional Minkowski space and a 4-dimensional instanton. We also construct D6-D8 bound state which preserves 1/2 supersymmetries. We then discuss massive IIA compactification on T4 and point out that when all possible RR fluxes on T4 are turned on the six-dimensional theory appears to assume a nice SO(4,4) invariant form. (author)