A system of nonautonomous differential equations having Chua's piecewise-linearity is studied. A brief discussion about equilibrium points and their stability is given. It is also extended to obtain a system showing "multispiral" strange attractors, and some of the fundamental routes to "multispiral chaos" and bifurcation phenomena are demonstrated with various examples. The same work is done for other systems of autonomous or nonautonomous differential equations. This is achieved by modifying Chua's piecewise-linearity in order to have additional segments. The evolution of the dynamics and a mechanism for the development of multispiral strange attractors are discussed.