Question: How do I save a matrix in an intermediate step of calculation?

I am working on an iterative code where I need to save a matrix in an intermediate step. My code is long and it uses a separate data file. So, I am trying to state my problem taking a simple example.

At first, I define a column matrix A0. Using A0, I do some calculations and test some conditions. 
In the next step, I want  to do similar calculations and test some conditions but this time by changing the first element of A0. For the purpose of later use, I need to save the matrix A0 in its original form. I am trying to use the following method but both A0 and A1 (modified A0) turn out to be same.

> restart;
> n := 3;
> A0 := Matrix(n, 1, 1);
> #Do some calculation with A0
> A1 := A0;
> A1[1, 1] := A1[1, 1]+.1*A1[1, 1];
> A1;
> print(A0, A1);

This might be because I set A1:=A0 in the third line. But how do I save A0 in its original form?