Intermission: The Pre-TC1
In order to provide a more complete overview of the operation of a CPU simulator, we are going to introduce a highly simplified, but complete, version to give you an idea of how things fit together, before we create a more complex system.
In this section, you will learn how to design a simulator without some of the complications associated with a fully fledged design.
This version of TC1, called TC1mini, can execute assembly language. However, we use a fixed format for assembly-level instructions (input is case-sensitive) and a fixed literal format (no hexadecimal or binary numbers), and we don’t support labels and symbolic names. This approach helps stop the details from getting in the way of the bigger picture.
The Simulator
The simulator supports register-to-register operations, such as ADD r1,r2,r3. Its only memory access is pointer-based, that is, LDRI r1,[r2] and STRI r1,[r2]. It provides increment and decrement instructions, INC r1...