What is the minimum set of instructions in a practical microprocessor? The CISC processors generally have 100 or more instructions. The RISC processors have about 50 instructions. In our investigations, it was obvious that 16 instructions are not sufficient to support all the necessary functions required in a microprocessor. 50 instructions are too many. The minimum number of instructions is somewhere between 16 and 32. A convenient choice is to limit the number of instructions to 32 and implement a microprocessor with 5 bit instructions.

In this thesis, I develop historical, qualitative, and quantitative distinctions between the first and second generations of stack computers. I present a rebuttal of the main arguments against stack computers and show that they are not applicable to those of the second generation. I also present an example of a small, modern stack computer and compare it to the MIPS architecture. The results show that second-generation stack computers have much better performance for deeply nested or recursive code, but are correspondingly worse for iterative code. The results also show that even though the stack computer’s zero operand instruction format only moderately increases the code density, it significantly reduces instruction memory bandwidth.