  We develop a version of controlled algebra for simplicial rings. This
generalizes the methods which lead to successful proofs of the algebraic K-
theory isomorphism conjecture (Farrell-Jones Conjecture) for a large class of
groups. This is the first step to prove the algebraic K-theory isomorphism
conjecture for simplicial rings. We construct a category of controlled
simplicial modules, show that it has the structure of a Waldhausen category and
discuss its algebraic K-theory.
  We lay emphasis on detailed proofs. Highlights include the discussion of a
simplicial cylinder functor, the gluing lemma, a simplicial mapping telescope
to split coherent homotopy idempotents, and a direct proof that a weak
equivalence of simplicial rings induces an equivalence on their algebraic
K-theory. Because we need a certain cofinality theorem for algebraic K-theory,
we provide a proof and show that a certain assumption, sometimes omitted in the
literature, is necessary. Last, we remark how our setup relates to ring
spectra.
