An overview of discrete linear control theory is given. Topics covered include: Dynamical systems and difference equations. The z-transform. The time and the frequency domain. Test responses - Impulse, step, ramp, parabolic. Initial value theorem and final value theorem. The poles and zeros of the transfer function. Stability. Aperiodicity. The Fourier transform and the frequency response. Random demands and variance analysis. Bullwhip and lead times