We give a unified description of self-dual SU(2) gauge fields on tori of si
ze l(t) X l(s)(3), based on a mixture of analytical and numerical methods u
sing the Nahm transformation, extended to the case of twisted boundary cond
itions. We show how torus calorons (l(t)/l(s) small) are Nahm dual to the t
orus instantons (l(t)/l(s) large). Holonomies are dual to the locations of
constituents, this duality becoming exact in the limiting cases l(s) or l(t
) --> infinity. Implications for the moduli spaces are discussed. (C) 2000
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