Abstract: The microprogram is the essential part of the computer which allows the interaction between hardware and software. In many processors, the microprogram executes machine code instructions directly on the hardware, providing a final level of interpretation between machine language instructions and the basic memory and arithmetic operations performed by the hardware. However, some new architectures do not implement a microprogram. Instead, operations in the digital logic level are run directly by software. In this project, I will examine microprogramming in terms of its role as the intersection of hardware and software, and in doing so, compare and contrast microinstruction-rich and microinstruction-deficient architectures, and examine various new approaches to hardware/software interaction.