  Let $(\tau_n)$ be a sequence of toral automorphisms $\tau_n : x \rightarrow
A_n x \hbox{mod}\ZZ^d$ with $A_n \in {\cal A}$, where ${\cal A}$ is a finite
set of matrices in $SL(d, \mathbb{Z})$. Under some conditions the method of
"multiplicative systems" of Koml\`os can be used to prove a Central Limit
Theorem for the sums $\sum_{k=1}^n f(\tau_k \circ \tau_{k-1} \cdots \circ
\tau_1 x)$ if $f$ is a H\"older function on $\mathbb{T}^d$. These conditions
hold for $2\times 2$ matrices with positive coefficients. In dimension $d$ they
can be applied when $A_n= A_n(\omega)$, with independent choices of
$A_n(\omega)$ in a finite set of matrices $\in SL(d, \mathbb{Z})$, in order to
prove a "quenched" CLT.
