The authors have been working in development of a FDTD dedicated computers for numerical simulation of electromagnetic fields. In the FDTD dedicated computers, there are two kinds of architectures which are oriented for very large scale simulations or high performance computations. In this paper, VHDL cording and FPGA implementation of the large scale simulation type of the FDTD dedicated computer are presented as the final stage of the FDTD machine developments. It is also shown that numerical simulations of microwave phenomena by the FDTD machine has good agreements with that of C language simulations.