A complete description of all new instructions, new or altered state, and any changes to existing ISA.

Whenever a new instruction set is introduced, it's important to describe each new instruction in detail. For each new instruction, we need to clarify:

• The mnemonic or name: This is usually a short, memorable code that programmers can use to invoke the instruction.

• The operation: What exactly does the instruction do? This can be a mathematical operation, a memory operation, a control flow operation, or something else.

• The operands: What inputs does the instruction need, and where do they come from? The operands could be in registers, in memory, or they might be immediate values specified directly in the instruction.

• The result: What is the output of the instruction, and where does it go? It might be a value written to a register, a change in memory, or an alteration of the program's control flow.

• Side effects: Does the instruction change anything else, such as condition codes or flags? If so, these need to be documented as well.

An instruction set architecture (ISA) may include new or altered state variables. State refers to all of the stored information that the CPU uses to execute programs, including:

• Registers: Registers are small amounts of storage that are directly accessible to the CPU. A new ISA might add new registers, or change the purpose or size of existing ones.

• Memory: The ISA may introduce changes to the memory model, such as new modes of addressing, new memory protection schemes, or changes in the virtual memory system.

• Control Registers and Flags: These are special registers used to control the operation of the CPU or to store status information. Any changes to these should be carefully documented.

If the new ISA changes any existing instructions, these changes need to be documented. This could include:

• Changes in the operation of an instruction.

• Changes in the number, type, or role of operands.

• Changes in the result or side effects.

• Removal of existing instructions.

• Changes in the encoding of the instructions in binary form.