Questions and Answers
What is the purpose of the interrupt service routine?
Where are the addresses of interrupt service routines stored?
Why must interrupts be handled quickly?
What is an interrupt vector?
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Why are tables of pointers used for handling interrupts?
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What is the main function of an interrupt mechanism in computer architecture?
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What is the main purpose of clustering in a clustered system?
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Which term describes the concept of a system being able to continue operation even after a failure of any single component?
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In a clustered system, what happens if a monitored machine fails?
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What is fault tolerance in the context of clustered systems?
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What is an example of asymmetric clustering in a clustered system?
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Why is redundancy added in clustered systems for achieving high availability?
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What must be provided due to the file system residing on secondary storage?
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What is the primary purpose of providing mechanisms for process synchronization and communication?
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Why is it important for an operating system to differentiate between operating-system code and user-defined code?
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What is the main reason for providing dual-mode and multimode operation in computer systems?
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Which aspect is NOT a primary concern addressed by the operating system and its design?
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What is the most significant reason for needing two separate modes of operation in a computer system?
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What type of memory is used to store the bootstrap program since RAM is volatile?
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What is the main function of main memory in a computer system?
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How is interaction achieved with different forms of computer memory?
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What does the load instruction do in relation to the CPU?
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Why does the CPU require data from disk to be transferred to main memory before processing?
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What happens during the fetch stage of an instruction cycle in a von Neumann architecture?
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In the context of memory management, what role does the CPU play in data processing?
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In what scenario does the CPU automatically load instructions from main memory for execution?
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What distinguishes main memory from other storage devices in a computer system?
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What does the store instruction do in relation to main memory?
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How does main memory support the operation of a modern computer system?
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Study Notes
Interrupts
- The fixed location usually contains the starting address where the service routine for the interrupt is located.
- The interrupt service routine executes, and on completion, the CPU resumes the interrupted computation.
- Interrupts are an essential part of a computer architecture.
- Each computer design has its own interrupt mechanism, but several functions are standard.
- The interrupt must transfer control to the appropriate interrupt service routine.
- A table of pointers to interrupt routines can be used to provide the necessary speed.
- The interrupt routine is called indirectly through the table, with no intermediate routine needed.
- The table of pointers is stored in low memory, holding the addresses of the interrupt service routines for various devices.
Storage Structure
- Since RAM is volatile, it cannot be trusted to hold the bootstrap program.
- Electrically erasable programmable read-only memory (EEPROM) storage is used instead, which is infrequently written to and nonvolatile.
- All forms of memory provide an array of bytes, each with its own address.
- Interactions are achieved through a sequence of load or store instructions to specific memory addresses.
- The load instruction moves a byte or word from main memory to an internal register within the CPU.
- The store instruction moves the content of a register to main memory.
CPU Execution Cycle
- A typical instruction (execution cycle) as executed on a system with a von Neumann architecture:
- Fetches an instruction from memory and stores it in the instruction register (CPU).
- The instruction is then decoded and may cause operands to be fetched from memory and stored in an internal register.
- If it is not in memory, then check and process for I/O interrupt.
Clustered Systems
- Clustered systems are composed of two or more individual systems—or nodes—joined together; each node is typically a multicore system.
- The generally accepted definition is that clustered computers share storage and are closely linked via a local-area network (LAN) or a faster interconnect.
- Clustering is usually used to provide high-availability service—that is, service that will continue even if one or more systems in the cluster fail.
- Each node can monitor one or more of the others (over the network).
- If the monitored machine fails, the monitoring machine can take ownership of its storage and restart the applications that were running on the failed machine.
Dual-Mode and Multimode Operation
- A properly designed operating system must ensure that an incorrect (or malicious) program cannot cause other programs—or the operating system itself—to execute incorrectly.
- The approach taken by most computer systems is to provide hardware support that allows differentiation among various modes of execution.
- At the very least, we need two separate modes of operation: user mode and kernel mode.
Memory Management
- The main memory is central to the operation of a modern computer system.
- Main memory is a large array of bytes, ranging in size from hundreds of thousands to billions.
- Each byte has its own address.
- Main memory is a repository of quickly accessible data shared by the CPU and I/O devices.
- The CPU reads instructions from main memory during the instruction-fetch cycle (van Neumann architecture).
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Description
Explore the characteristics and structure of clustered systems, where two or more individual systems are connected together to share storage and provide high-availability services. Learn about the general structure of clustered systems and how nodes are linked via a local-area network.
