Question

1.  An ISA may be implemented by many different processor circuits. Why is this of value in the marketplace?
2. What data structure is used by the machine code program placed in the instruction memory of a fixed-length instruction representation processor?

3. The bit strings of a machine code program can be thought of as having a type. What is a reasonable name for this type?

Answer 1

1.  An ISA is the same as Compiler writer model, as we know programming model of a processor in assembly language.and we can say it is an abstract model of a computer, also referred to as computer architecture.

Marketplace value due to below reason:

• An ISA permits multiple implementations that may vary in its performance, physical size, and cost
• ISA acts as INterface between hardware and software
• Software written in ISA can implementation on the same ISA
• Binary compatibility between different generations of computers enabled in this
• Machines with different microarchitectures may have the same instruction set architecture, and thus be capable of executing the same programs. New microarchitectures and/or circuitry solutions, along with advances in semiconductor manufacturing, are what allows newer generations of processors to achieve higher performance while using the same ISA

2. Machine code, consisting of machine language instructions, is a low-level programming language used to directly control a computer's central processing unit (CPU). Machine code written in binary.

• Machine language instructions consists of several bytes in memory that tells the processor to perform one machine operation
• The processor comes at machine instructions in main memory one after another, and performs one machine operation for each machine instruction
• The collection of machine instructions in main memory is called a machine language program.
• Machine language is a set of instructions that executed directly by a computer’s central processing unit (CPU).
• Instruction performs a very specific task, such as a load, a jump, or an ALU operation on a unit of data in a CPU register or memory. E

The format of a machine instruction is

Label   Mnemonic [Operand, Operand].    [; Comments]

EX: ADD, SUB: Add, subtract byte or word