The Postroom Computer

The Postroom Computer is a computer architecture simulator based on the Little Man Computer developed in 1965 by Stuart Madnick and John Donovan. It provides a family of architectures suitable for use in teaching introductory computer architectures. It is designed to introduce aspects of computer architecture and low-level programming in an incremental way. The extensions are designed to provide a range of computing models within the Little Man Computer paradigm. As they are introduced they can be related both to the Little Man Computer paradigm and to "real" machines. The two major extensions are a range of instruction set architectures---0, 1, 2, and 3 address machines, and a choice of addressing architectures---immediate or register operands---with a range of memory models with or without registers and/or background memory.The extensions have a high degree of orthogonality, allowing concepts to be introduced in an incremental fashion. It would, in fact, be more correct to speak of a family of Postroom Computers, rather than one Postroom Computer.