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Memory addressing:
Register addressing - Addressing the registers within a CPU or other special purpose registers that are designated in the primary memory.
Direct addressing - Addressing a portion of primary memory by specifying the actual address of the memory location. The memory addresses are usually limited to the memory page that is being executed or page zero.
Absolute addressing - Addressing all of the primary memory space.
Indexed addressing - Developing a memory address by adding the contents of the address defined in the program's instruction to that of an index register. The computed, effective address is used to access the desired memory location. Thus, if an index register is incremented or decremented, a range of memory location can be accessed.
Implied addressing - Used when operations that are internal to the processor must be performed such as clearing a carry bit that was set as a result of an arithmetic operation. Because the operation is being performed on an internal register that is specified within the instruction itself, there is no need to provide an address.
Indirect addressing - Addressing where the address location that is specified in the program instruction contains the address of the final desired location.
CPU Modes and Protection Rings:
Protection rings - Provide strict boundaries and definitions on what the processes that work within each ring can access and what commands the can successfully execute. The processes that operate within the inner rings have more privileges, privileged / supervisor mode, than the processes operating in the outer rings, user mode.
Operating states:
Ready state - An application is ready to resume processing.
Supervisory state - The system is executing a system, or highly privileged, routine.
Problem state - The system is executing an application.
Wait state - An application is waiting for a specific event to complete, like the user finishing typing in characters or waiting for a print job to finish.
Multi-threading, -tasking, -processing:
Multithreading - One application can make several calls at one time, that use different threads.
Multitasking - The CPU can process more than one process or task at one time.
Multiprocessing - If a computer has more than one CPU and can use them in parallel to execute instructions.
Input/Output Device Management:
Deadlock situation - If structures are not torn down and released after use. Resources should be used by other programs and processes.
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