  It is well-known that the coordinate as a continuous variable, consisting of
a set of all points between 0 and $L$ contradicts the observability of
measurement. In other words there might exist a fundamental length in nature,
such as the Planck length $\lambda_P$, so that it is not possible to measure a
position coordinate with accuracy smaller than this fundamental length. It is
therefore necessary to investigate the formulation of quantum mechanics using
only discrete variables as coordinates. To investigate all of quantum mechanics
or any branch of physics from this approach is of course a daunting task and
thus it is worthwhile to consider a specific simple problem in order to
formulate the basic ideas. In this note we compare the solutions of Schrodinger
equation for one-dimensional free particle under the usual space-time continuum
with those that are obtained when space-time is assumed to be quantized using a
simple model. For this purpose, we replace the derivatives occurring in
Schrodinger equation with the corresponding discrete derivatives. We compute
the probability density (and the probability current) under the two scenarios;
they turn out to be quite different in the two cases. We also obtain the
operator identity for the commutator $[p,x]^q$ under the assumption of
quantized space-time and contrast it with the usual commutator $[p,x]$.
