A FPGA based Forth microprocessor

Systems which employ a microprocessor together with an application specific FPGA based coprocessor are common today. These applications can reduce power consumption and system costs by incorporating the microprocessor in the FPGA. For such applications, a microprocessor which has good performance, occupies a minimal amount of FPGA resources, has a good high level language software development environment and good code density is desirable. In this paper a 16 bit FPGA based microprocessor, called MSL16, optimised for such applications is described. MSL16 utilises a stack architecture with each instruction occupying only 4 bits, leading to a small instruction set, simple datapath and control, and high code density. MSL16 was specifically designed to efficiently execute the programming language "Forth". The Forth language has the desirable features of portability and high code density, and it is well suited to control, DSP, real-time and embedded applications.