RTL stands for Register Transfer Language. The Register Transfer Language provides a formal way for the description of the behavior and structure of a computer. The RTL facilitates the design process of the computer as it provides a precise, mathematical representation of its functionality. (Page 66)
Addressing modes are the different ways in which the CPU generates the address of operands. In other words, they provide access paths to memory locations and CPU registers. (Page 39)
To ensure the correct and controlled execution of instructions in a program, and all the related operations, a timing device is required. This is to ensure that the operations of essentially different instructions do not mix up in time. There exists a 'timing step generator' that provides mutually exclusive and sequential timing intervals. (Page 152)