Computer Architecture Basics Quiz

Chapter 1: Introduction

• Introduction to operating systems
• Attendance requirements: 70% for courses and 80% for labs.
• Key components of computer systems: hardware, operating system, application programs, and users.
• Objectives: describe computer system organization, role of interrupts, modern multiprocessor systems, transition from user mode to kernel mode, use of operating systems in various computing environments, and examples of free and open-source operating systems.
• Computer system structure: Hardware (CPU, memory, I/O devices), Operating system (controls hardware, manages applications and users), Application programs (solve user problems, use system resources), and Users (people, machines, other computers).
• Abstract view of computer components: users interact with application programs, which in turn interact with operating system, which interacts with computer hardware.
• What operating systems do: provide convenience, ease of use, and good performance for users. Handle resource allocation and control amongst users and applications.
• Defining operating systems: wide range of functions, from toasters to ships.
• Operating system definition: everything a vendor ships, one program running continuously (the kernel), system programs, application programs.
• Computer system organization: CPUs and devices connect via a bus to access shared memory and operate concurrently.
• Computer system operation: I/O devices and CPU operate concurrently. Device controllers control specific types of devices, have local buffers, and use drivers. I/O transfers data between devices and CPU via local buffers and can be interrupted.
• Common Functions of Interrupts: transfer control to the interrupt service routine(generally through the interrupt vector), save address of interrupted instruction. A trap/exception is a software generated interrupt caused by an error or user request. OS is interrupt driven.
• Interrupt Timeline: Shows the interaction between the CPU and I/O device, illustrating the interrupt process.
• Computer Startup: bootstrap program loaded at power-up or reboot. Typically stored in ROM or EPROM. Initializes all aspects of the system and loads the OS kernel.
• Interrupt Handling: OS preserves CPU state (registers and program counter). Determines interrupt type, and executes actions defined for each type of interrupt through polling or vectored interrupt system.
• Interrupt-driven I/O Cycle: Steps showing how CPU responds to an I/O request , the transfer of data , and resumption of the interrupted task.
• I/O Structure: Control returns to the user program only after I/O is complete, wait instructions, and I/O requests. I/O devices and memory management details including buffering, caching, and spooling.
• Storage Structure: CPU only loads from memory. Main memory (RAM) is volatile (data lost on power off), while secondary storage (HDD, NVM) offers non-volatile storage. Disk drives use tracks and sectors.
• Storage Structure 2: Bootstrap program that runs first during start-up. RAM is volatile therefore use EEPROM/firmware(non volatile) for storage of important data, example iPhone uses EEPROM.
• Storage Definitions and Notation Review: basic unit is bit, then bytes (typically 8 bits), word ( native unit of computer/system data), kilobytes (KB, 1024 bytes), megabytes (MB), gigabytes (GB), terabytes (TB), and petabytes (PB) for computer storage.
• Storage Hierarchy: Main memory, secondary storage, and tertiary storage are organized in a hierarchy based on speed, cost, and volatility. Caching (copying data to faster storage) is a key idea in memory management.
• Storage-Device Hierarchy: Registers are the top of the hierarchy, followed by cache, main memory, secondary/hard disk drives, followed by tertiary storage (optical disks, magnetic tape).
• How a Modern Computer Works: execution threads, instruction execution/cycle, data movement. DMA(direct memory access)- transfer data from storage to memory without CPU intervention - reduces contention for memory cycle
• Direct Memory Access Structure: Used with I/O devices transmitting information extremely rapidly. Data transferred in blocks.
• Computer-System Architecture: mostly use single general-purpose processor but special-purpose processors also exist. Multiprocessors (parallel systems, tightly-coupled systems) improve throughput and reliability through graceful degradation and fault tolerance. Asymmetric and symmetric multiprocessing.
• Symmetric Multiprocessing Architecture: processors have similar functionality.
• A Dual-Core Design: shows the components of a dual-core system
• Non-Uniform Memory Access System (NUMA): Improves performance by allowing each CPU to have its own local memory and interconnect rather than all accessing a shared bus limiting bottlenecks.
• Clustered Systems: Multiple interconnected systems that may use storage-area network (SAN) or provide high availability services. Asymmetric or symmetric clustering models. High-performance computing (HPC) clusters.
• Clustered Systems Diagram: Shows networked computers with shared storage.
• PC Motherboard: components include processor socket, DRAM slots, and various I/O/power connectors. PCI bus slots.
• Operating-System Operations: functions of bootstrap program, kernel, kernel interrupt (hardware and software), and software interrupts (exception/trap). System calls.
• Multiprogramming and Multitasking: techniques for running multiple programs needed for efficiency to keep CPU busy. Job scheduling. Timesharing (multitasking) provides fast response time.
• Memory Layout for Multiprogrammed Systems: organizes memory layout with OS at top and various process segments below.
• Dual-Mode and Multimode Operation: hardware provides user mode and kernel mode(0 - kernel, 1 - user). Privileged instructions only executable in kernel mode. System call changes mode from user to kernel. Virtual machine Manager (VMM)
• Transition from User to Kernel Mode: prevents infinite loops. Process hogging CPU resources. Timer interrupts.
• Process Management: a process is an active program execution within system. Processes need resources(CPU, memory, I/O, files), data and termination for resource reclaimation. Single-threaded and multi-threaded processes. Concurrency via multithreading and CPU multiplexing
• Process Management Activities: creating, deleting, suspending/resuming, synchronization, communication, and deadlock handling.
• Memory Management: ensures correct placement of instructions and data in memory to optimize CPU usage and computer response. Tracks processes using memory, moves processes into or out of memory to allow other processes access, assigns memory space for needed processes.
• File-system Management: provides uniform view of data storage. Abstracts physical properties of storage (i.e. disk drive) into logical blocks or files. Organization into directories. Access controls. OS activities for creating, deleting, manipulating files, mapping data, and backing up on secondary storage.
• Mass-Storage Management: manages secondary storage (disks, tapes) as it is critical to performance. Disk scheduling, free space management, mounting/unmounting, partitioning, and protection.
• Caching: reduces access time by copying frequently used data into faster cache memory.
• Characteristics of Various Types of Storage: different storage devices, their properties, e.g., typical size, implementation, access time, bandwidth and management.
• Migration of data: multitasking systems must ensure proper access for data no matter where in storage hierarchy it is.
• Cache Coherency: keeps multiple caches synchronized (in multiprocessor systems) for correctness.
• I/O Subsystem: hides hardware device peculiarities from users to provide uniform interface. Includes functions like buffering, caching, and spooling.
• Protection and Security: mechanisms for controlling access to system resources and preventing internal/external attacks e.g. denial of service, worms, viruses. User IDs, security IDs, controls.
• Virtualization: allows multiple operating systems to run on the same physical hardware. Emulation, interpretation, VM concepts. VM's manage the virtualization services.
• Virtualization (cont.): Use cases such as running multiple OS on laptops, developing applications for various systems, testing applications, managing compute environments, and hosting multiple systems.
• Computing Environments - Virtualization Diagram: shows a computer with a single OS or multiple virtual machines running applications in a virtual environment
• Distributed Systems: Collection of interconnected, possibly heterogeneous, systems working together through communication paths like LAN, WAN, MAN , PAN.
• Distributed Systems Diagram: Example network diagram illustrating the connections between multiple computer systems.
• Kernel Data Structures: data organization methods like linked lists, doubly linked lists, circular linked lists and trees. Binary search trees. Hash functions, hash maps and bitmaps.
• Computing Environments - Traditional: Standalone computers, and network computers, and networking, and internet connected computers.
• Computing Environments - Mobile: Features of mobile systems, including specific functions (GPS and gyroscope) and connectivity via wireless networks and data networks.
• Computing Environments - Client-Server: Clients request services from servers (including compute and file services).
• Computing Environments - Peer-to-Peer: A network architecture where all nodes are considered peers, each able to act as client or server, and using lookup protocols for communication.
• Computing Environments - Cloud Computing: Logical extension of virtualization, delivery of computing resources like servers, storage, and applications over a network. Different types: private, public, and hybrid. Services: SaaS, PaaS and IaaS.
• Computing Environments - Cloud Computing (Diagram): Illustrates the architecture of a cloud computing environment with elements like internet, load balancer, firewall, and various virtual machines, storage and cloud services.
• Computing Environments - Real-Time Embedded Systems: computers and OS’s designed to respond to events within specific time constraints like real-time OS’s, which handle processing and operations within the time constraints.

Free and Open-Source Operating Systems

• Available in source-code format, not just binary.
• Supported by the Free Software Foundation (FSF) with "copyleft" GNU Public License (GPL).
• Examples include GNU/Linux, BSD UNIX, and others.
• Useful for running guest OS in order to explore and test.

The Study of Operating Systems

• Open-source movement is driving the study of operating systems.
• Availability of source code makes understanding systems easier.
• Virtualization makes it possible to run many operating systems on one physical machine.
• The study of operating systems is more accessible and relevant than it has ever been.

Test your knowledge on fundamental concepts in computer architecture, such as data units, storage measurements, and the relationship between bytes and native word sizes. This quiz covers essential topics for understanding computer systems and their functionality.