cda levels

Level 0 digital logic level

This level is where we find digital circuits (the chips).

 

•Digital circuits consist of gates and wires.

 

•These components implement the mathematical logic of all other levels.

Level 1: Control Level

A control unit decodes and executes instructions and moves data through the system.

•Control units can be microprogrammed or

hardwired.

•A microprogram is a program written in a low-level language that is implemented by the hardware.

•Hardwired control units consist of hardware that directly executes machine instructions.

Level 2: Machine level

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

•Consists of instructions that are    particular to the architecture of the    machine.

•Programs written in machine    language need no compilers,    interpreters, or assemblers.

Level 3: System Software Level

•Controls executing processes on the system.

•Protects system resources.

•Assembly language instructions often pass-through this Level without modification.

Level 4: Assembly Language Level

•Acts upon assembly language produced from the level above, as well as instructions programmed directly at this level.

•Level 5: High-Level Language Level

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

Level 6: The User Level

Program execution and user    interface level

•The level we are most familiar with