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Central Processing unit (CPU)
A microprocessor is the electronic circuitry that performs the computer arithmetic, logic, and computing functions in the main component of the computer architecture.
Arithmetic Logic Unit (ALU)
Performs numerical calculations and comparative logic functions.
Bus Interface Unit (BIU)
Supervises data transfers of bus systems between the CPU and I/O devices.
Control Unit
coordinates activities of the other CPU components during program execution.
Decode Unit
Converts incoming instructions into individual CPU commands.
Memory Management Unit (MMU)
Handles addressing and cataloging data thats stored in memory and translates logical addressing into physical addressing.
Pre-Fetch Unit
Preloads instructions into CPU registers.
Protection Test Unit (PTU)
Monitors all CPU functions to ensure that they are properly executed.
Registers
Buffers that temporarily hold CPU data, addresses, and instructions.
Fetch and execute
Distinct phases of the microprocessor. During the fetch phase, the CPU locates and retrieves a required instruction from memory.   During the execute phase the CPU decodes and executes instructions.
4 operating states of a CPU
1. Operating (run): CPU executes an instruction or instructions.
2. Problem (application): CPU calculates a solution to an application-based problem. only a limited subset of instructions (non-privileged)is available.
3. Supervisory:  CPU executes a privileged instruction, meaning that instructions is only available to system admin or authorized user/process.
4. Wait: CPU hasnt yet completed execution of an instruction and must extend the cycle.
Scalar and superscalar CPU
Scalar: executes a single instruction at a time

superscalar: execute multiple instructions concurrently.
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