Chapter 9

1. Possible uses:

• To run a binary program for a computer when that computer is not available
• To debug or analyze a binary program when its source code is not available
• To disassemble machine code
• To translate a binary program into another machine language
• To translate a binary program into a high-level programming language

2. It is the main data register. It is the default source and destination of any instruction.
3. It is the main address register. It contains the address of the next instruction that will be fetched and executed.
4. One reason is that the use of numbers is more error-prone than the use of names. The other is that when an instruction or a variable is added or removed, the addresses of all the following instructions or variables change, and so a lot of addresses in code must be incremented or decremented.

5. Defining a variant for every instruction type. The name of the variant is the symbolic name of the instruction, and its parameters are the types of the operands...