Review:Chapter 1Operating Systems– exploit the hardware resources of one or more processors and provide a set of services to system users. They also manage secondary memory and I/O devices. The OS is responsible forcontrolling the use of a computer’s resources, such as I/O, main and secondary memory, and processor execution time. Functions in the same way as ordinary computer software. Program, or suite of programs, executed by the processor.Frequently relinquishes control and must depend on the processor to allow it to regain controlProcessor– Also referred as CPU. Controls the operation of the computer and performs the processing of dataMain Memory– Stores data and programs. It’s typically volatile.I/O modules – Move data between the computer and its external environment. Secondary memory (disks), communication equipment, terminalsSystem Bus– Provides communication among processors, main memory, and I/O modulesMicroprocessor – Invention that brought about desktop and handheld computing. Contains a processor or a single chip. Graphical Processing Units (GPU)– Provide efficient computation on arrays of data using single-instruction multiple data techniques pioneered in supercomputers.Digital Signal Processors (DSP)–Deal with streaming signals, such as audio or videoSystem on a Chip (SoC)– To satisfy the requirements of handheld devices, the classic microprocessor is giving way to the SoCInstruction Execution – A program consists of a set of instructions stored in memory. Processor reads (fetches) instructions from memory, then executes instructionInstruction Cycle– The processing required for a single instruction. Start -> fetch -> Execute -> Loop/HaltThe processor fetches an instruction from memory (where?). Typically, the program counter holds the address of the next instruction to be fetched. And then PC is incrementedInstruction Register– Fetched instruction is loaded into instruction register. Processor interprets the instruction and performs required action. Instruction being executedOpcode –Program Counter (PC)– Address of the instructionAccumulator (AC)– Temporary storageInterrupts– Mechanisms by which other modules may interrupt the normal sequencing of the processor. Provided to improve processor utilization
Program– Generated by some condition that occurs as a result of an instruction execution, such as arithmetic overflow, division by zero, attempt to execute an illegal machine instruction, and reference outside a user's allowed memory space.Timer– Generated by a timer within the processor. This allows the operating system to perform certain functions on a regular basis.I/O– Generated by an I/O controller, to signal normal completion of an operation or to signal a variety oferror conditions.