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Paper 2: Operating Systems I
This Paper 2 course is taken by Part IA Computer Science Tripos students only.
Lecturer: Dr S.M. Hand
No. of lectures: 17 (Continued into Lent Term)
Prerequisite course: Digital Electronics.
This course is a prerequisite for the Part IB courses Concurrent Systems and Applications and Introduction to Security, and the Part II courses Advanced System Topics, Distributed Systems and Security.
Aims
The overall aim of this course is to provide a general understanding of how a computer works. This includes aspects of the underlying hardware as well as the structure and key functions of the operating system. Case studies will be used to illustrate and reinforce fundamental concepts.
Lectures
- Computer organization. History: from vacuum
tubes to VLSI. Von Neumann architecture. Hardware/software layers
and languages. Operation of a simple computer (processors,
memory, buses, devices). Memory: concepts, structures, hierarchy.
Processor: control and execution units. ALU and computer
arithmetic. Logical and conditional operations. Branches. Memory
access. Data representation: (integers), text, reals, compound
structures, instructions. Fetch-Execute cycle revisited. General
I/O architecture. Example devices. Buses: general operation,
hierarchy, synchronous versus asynchronous. Interrupts.
Direct Memory Access. Programming in assembly. [5 lectures]
- Introduction to operating systems. Abstract view of an
operating system. OS evolution: multi-programming, time-sharing.
Dual-mode operation. Protecting I/O, memory, CPU. Kernels and
micro-kernels. [1 lecture]
- Processes and scheduling.
Job/process concepts. Scheduling basics: CPU-I/O interleaving, (non-)preemption, context
switching. Scheduling algorithms: FCFS, SJF, SRTF, priority
scheduling, round robin. Combined schemes. [2 lectures]
- Memory management. Processes in memory. Logical
addresses. Partitions: static versus dynamic, free space
management, external fragmentation. Segmented memory. Paged memory:
concepts, internal fragmentation, page tables. Demand
paging/segmentation. Replacement strategies: OPT, FIFO, LRU (and
approximations), NRU, LFU/MFU, MRU. Working set schemes. [2 lectures]
- I/O subsystem. General structure. Polled mode versus interrupt-driven I/O. Application I/O interface: block
and character devices, buffering, blocking versus non-blocking
I/O. Other issues: caching, scheduling, spooling, performance.
[1 lecture]
- File management. File concept. Directory and storage
services. File names and meta-data. Directory name-space:
hierarchies, DAGs, hard and soft links. File operations. Access
control. Existence and concurrency control. [1 lecture]
- Protection. Requirements. Subjects and objects. Design
principles. Authentication schemes. Access matrix: ACLs and
capabilities. Combined scheme. Covert channels. [1 lecture]
- Unix case study. History. General structure. Unix file
system: file abstraction, directories, mount points, implementation
details. Processes: memory image, life cycle, start of day. The
shell: basic operation, commands, standard I/O, redirection, pipes,
signals. Character and block I/O. Process scheduling. [2 lectures]
- Windows NT case study. History. Design principles.
Overall architecture. HAL. Kernel: objects, processes, threads,
scheduling. Executive: object manager and object namespace, process
manager, VM manager, I/O manager. File-System. Security
System. [2 lecture]
Objectives
At the end of the course students should be able to
- describe the fetch-execute cycle of a simple computer with
reference to the control and execution units
- understand the different types of information which may be
stored within a computer memory
- explain the concepts of process, address space, and file
- compare and contrast various CPU scheduling algorithms
- understand the differences between segmented and paged memories,
and be able to describe the advantages and disadvantages of each
- compare and contrast polled, interrupt-driven and DMA-based
access to I/O devices
Recommended reading
Tanenbaum, A.S. (1990). Structured computer organisation. Prentice Hall (3rd ed).
Patterson, D. & Hennessy, J. (1998). Computer organisation and design. Morgan Kaufmann (2nd ed.).
* Bacon, J. & Harris, T. (2003). Operating systems. Addison-Wesley (3rd ed.).
Silberschatz, A., Peterson, J.L. & Galvin, P.C. (2005). Operating systems concepts. Addison-Wesley (7th ed.).
Leffler, S. (1989). The design and implementation of the 4.3BSD Unix operating system. Addison-Wesley.
Solomon, D. & Russinovich, M. (2000). Inside Windows 2000. Microsoft Press (3rd ed.).




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