Layered Architecture Table

Level 0	Digital logic ·     Contains digital circuits, consisting of gates and wires ·     Implements mathematical logic of all other level.
Level 1	Control ·     Control unit decodes and executes instructions and moves data through the system
Level 2	Machine ·     Also known as Instruction Set Architecture level ·     Consists of instructions that are particular to the architecture of the machine
Level 3	Systems Software ·     Consists of Operating System and Compliers, interpreters and assemblers
Level 4	Assembly language ·     Acts upon assembled language from level 5
Level 5	High-level language ·     The level in which programmers write programs, e.g. Java, C++, etc.
Level 6	User ·     Program execution and user interface

•       Level 6: User

•       Program execution and user interface

•       The level with which we are most familiar

•       Level 5: High-Level Language

•       The level with which we interact when we write programs in languages such as C, C++, Lisp, and Java

•       Level 4: Assembly Language

•       Acts upon assembled (compiled) language produced from Level 5

•       Acts upon instructions programmed directly at this level

•       Level 3: System Software

•       Operating system

•       Controls executing processes on the system

•       Protects system resources

•       Compilers, interpreters and assemblers

•       Translate programs into machine language

•       Responsible for multiprogramming, protecting memory, synchronizing processes etc.

•       Level 2: Machine

•       Also known as the Instruction Set Architecture (ISA) Level

•       Machine Language - programs written in machine language on a hardwired computer can be executed directly through the electronic circuit without interpreters, translators or compilers.

•       Level 1: Control Unit

•       Decodes and executes instructions

•       Interprets the machine instructions passed to it, one at a time, from the level above, causing the required actions to take place.

•       Moves data through the system

•       Level 0: Digital Logic

•       Where we find the physical components of the computer system: the digital circuits (the chips), which consist of gates and wires

•       Common to all systems.