Computer System Hierarchy

The computer system can be abstracted into multiple hierarchical layers, each building upon the previous one. Here is a typical nine-layer model:

Physical Layer:
Electronic devices operate based on the movement of electrons, which can be described using quantum mechanics and Maxwell’s equations.
Device Layer:
Electronic components are constructed by leveraging the movement of electrons in different materials (e.g., semiconductors, resistors, capacitors).
Analog Circuit Layer:
Amplifiers, filters, and other analog circuit components are built at this level. These circuits operate with continuous voltage.
Digital Circuit Layer:
Using analog circuit elements, digital logic gates such as AND, OR, and NOT gates are constructed to process discrete signals.
Logic Layer:
Combines digital circuits to implement arithmetic logic units (ALUs), registers, and other logical components.
Microarchitecture Layer:
Defines how the processor’s components (ALUs, registers, caches, pipelines) are organized and interact to execute instructions.
Instruction Set Architecture (ISA) Layer:
The interface between hardware and software, defining the set of instructions the processor can execute.
Operating System Layer:
Manages hardware resources and provides services for application software, such as process management, memory management, and file systems.
Application Software Layer:
User-facing programs and applications that perform specific tasks, such as word processors, web browsers, and games.

Note:

Each layer abstracts the complexity of the layer below it, making it easier to design, implement, and use computer systems.
Understanding this hierarchy helps in grasping how high-level software interacts with low-level hardware.

References