EEN521 Study Guide (19th November 1998)

• Be familiar with the general architecture of a CPU, its busses, and memory components.
• Memory management:
  • Hardware support:
    • Base and Limit address translation
    • Associative memory to map virtual addresses to physical addresses
    • Dividing memory into pages, only mapping page numbers, not offsets
    • Page faults and access violations
  • Software support:
    • Page tables in process control block
    • Actions on receiving a page fault
    • Hard page fault vs. soft page fault
    • The page file; paging out vs. swapping out
    • Page replacement strategies:
      • Optimal, Least-Recently-Used, FIFO, etc.,
      • Belady's anomaly
    • Actions on process time quantum expiring (when timesharing)
• File Systems:
  • Be familiar with physical structure of discs etc:
    • Tracks, Sectors, Blocks, Cylinders, Surfaces,
    • Rotational Latency, Track-to-track Seek time, estimating access times.
  • File Structures:
    • File formats (organising a set of blocks to make a file):
      • Direct, n-Level-Index, Inodes, etc.
      • Contents and purpose of header blocks
    • Directories, file protection, ownership, etc.
  • Disc Structures:
    • Special "files": superblock, boot block, etc.
    • Formatting a disc
    • Free Block Allocation:
      • FAT, Free-list, Inode-list.
    • Clusters and Partitions

----------------------1st test, 29th September------------------

• Input/Output Subsystem:
  • Levels of I/O calls (e.g. getchar(), read(), qio(), etc.)
  • Support for "non blocking" i/o.
  • Life of an Input/Output Request Packet (IRP)
  • Activities of a Device Driver
  • Disc Scheduling Strategies: FCFS, SSTF, Scan, etc.
  • Special files: file soft links, NFS mounted directories
  • System-wide and Process Open File List: what and why.
• Processes:
  • Representation in O.S.: PCBs, etc.
  • Attributes: State, Status, Priority, Mode, IPL, Privileges
  • Life Cycle of a process
  • Meaning of status:
    • Init, Current, Computable, Running, Stopped,
    • Idle, Sleep, Disc wait, Page wait,
    • Swapped out, Zombie
  • Scheduler and Scheduler Queues
  • In-Process management of memory:
    • Separate code, static, heap, and stack areas
• Inter-Process Communications
  • Problems caused by concurrent read & write access
  • Critical Sections,
  • Semaphores:
    • What they do and how and where they are used,
    • How they are implemented (atomic test and set, etc.)
  • Shared Resources in general:
    • Allocation problems (CR+LP example) and solutions:
      • Deadlock, Ordering, Livelock, etc.
    • Dining Philosophers and correspondence with O.S. and solutions:
      • Butler, Fork Boy, Fork Monster, Murderer.
• Networking
  • Ethernet
    • The idea behind it
    • Why collisions occur, and are not really faults.
    • Problems caused by having the wrong network layout
  • Addressing and Routing of packets
    • IP addresses, structure and meaning, vs. Hardware addresses
    • Routers, Bridges, and Repeaters
    • Address resolution: ARP, RARP, IP-Hardware address mapping
  • The main layers: Hardware, IP, TCP/UDP, Application
    • Their inter-relationships, how they work together
    • Their individual responsibilities
      • IP: routing, datagram delivery
      • TCP: connections, reliability, port numbers
    • Structure of packets (just generalities)
    • Protocols: (don’t try to learn them, just understand them)
  • Implementation
    • The structure of an internet client and server
    • The main operations:
      • socket(), connect(), bind(), listen(), accept()
  • Network File Servers
    • Principles of operation: RPC (Remote Procedure Call)
    • Stateless vs. “Stateful”, the arguments for and against each

----------------------------2nd test, 19th November-----------------------------

• Encryption-based Security
  • Why the common exclusive-or scheme is rubbish
  • One-way hash functions: how they work, what they are good for
  • One-time pads: how they work, why they are unbreakable
  • DES: just the general idea, its advantages and disadvantages
  • RSA (public key): general idea, advantages and disadvantages
  • The importance of selecting a long-enough key
  • feasibility of cracking by trying every possible key

---------------Final Examination, 5pm Thursday 10th December----------------