Instruction cpu Set

The ISA is the interface between the software and hardware                    . It is the set of instructions that bridges the gap between high level languages and the hardware.

1. For a processor to understand a command, it should be in binary and not in High Level Language. The ISA encodes these values.
2. The ISA also defines the items in the computer that are available to a programmer. For example, it defines data types, registers, addressing modes, memory organization etc.
3. Register are high speed storage for numbers that can be accessed by a processor. Data as well as instructions can be in a register.

Addressing modes are the ways in which the instructions locate their operands.
Memory organization defines how instructions interact with the memory.

[edit] Computer Organization

Computer organization helps optimize performance-based products. For example, software engineers need to know the processing ability of processors. They may need to optimize software in order to gain the most performance at the least expense. This can require quite detailed analysis of the computer organization. For example, in a multimedia decoder, the designers might need to arrange for most data to be processed in the fastest data path.
Computer organization also helps plan the selection of a processor for a particular project. Multimedia projects may need very rapid data access, while supervisory software may need fast interrupts.
Sometimes certain tasks need additional components as well. For example, a computer capable of virtualization needs virtual memory hardware so that the memory of different simulated computers can be kept separated.
The computer organization and features also affect the power consumption and the cost of the processor.

[edit] Design goals

The exact form of a computer system depends on the constraints and goals for which it was optimized. Computer architectures usually trade off standards, cost, memory capacity, latency and throughput. Sometimes other considerations, such as features, size, weight, reliability, expandability and power consumption are factors as well.
The most common scheme carefully chooses the bottleneck that most reduces the computer's speed. Ideally, the cost is allocated proportionally to assure that the data rate is nearly the same for all parts of the computer, with the most costly part being the slowest. This is how skillful commercial integrators optimize personal computers