PLATFORM TECHNOLOGY REVIEWER.pdf

PLATFORM TECHNOLOGY REVIEWER MODULE 1 Operating System (OS) - utilizes hardware resources of one or more processors to provide a wide range of services to system users. OBJECTIVES OF AN OPERATING SYSTEM: An operating system make...

PLATFORM TECHNOLOGY REVIEWER MODULE 1 Operating System (OS) - utilizes hardware resources of one or more processors to provide a wide range of services to system users. OBJECTIVES OF AN OPERATING SYSTEM: An operating system makes a computer convenient to use. An operating system allows computer resources to be utilized in an efficient manner. Operating systems are generally constructed to effectively support the development, testing, and implementation of new system functions or software applications. Program development - provides variety of facilities and services. Also called application program development tools. Program execution - handles different processes which must be performed to execute programs. Access to I/O devices - provides a uniform interface. Control access to files - detailed understanding of structure of data contained in file storage, control file access. System resource access - controls access to the whole system. Error detection and response - detect errors. Performance parameter monitoring - collect usage statistics from various processes. Instruction Set Architecture (ISA) - collection of machine language instructions that a computer can follow. Application Binary Interface (ABI) - standard for binary portability. Application Program Interface (API) - allows a program to the hardware resources and services. OPERATING SYSTEMS EVOLVE OVER TIME FOR THE FOLLOWING REASONS: Hardware upgrades or new types of hardware New or improved services Fixes to existing OS faults EVOLUTION OF OS: 1. Serial Processing - Computers are run from a console consisting of display lights, toggle switches, an input device, and a printer. Serial Processing 2 Main Problems: Scheduling - Installations used a hardcopy sign-up sheet to reserve computer time. Set-up time - A single program, called a job, involves numerous sequenced set- up processes. 2. Simple Batch Systems - The monitor provides automatic job sequencing as indicated by the control cards. 3. Multi-programmed Batch Systems - Allows the processor to handle multiple jobs at a time. 4. Time-sharing Systems - Multiple users simultaneously access the system. 5. Compatible Time-sharing System (CTSS) - First time-sharing operating systems. KERNEL COMPONENTS OF MICROSOFT WINDOWS OS: Windows Executive – contains the core OS modules/services. Functions: I/O manager - provides a framework Cache manager – improves the performance of file-based I/O. Object manager – creates, manages, and deletes Windows Executive objects Plug-and-play manager – determines which drivers are required Power manager - coordinates power consumption. Security reference monitor – enforces the access validation. Virtual memory manager – manages virtual addresses. Process/thread manager – creates, manages, and deletes processes and thread objects. Configuration manager – managing the system registry. Advanced local procedure call (ALPC) facility – cross-process call mechanism. Windows Kernel – core software of the OS. Hardware abstraction layer (HAL) – isolates the OS from platform-specific hardware. Device drivers – dynamic libraries that extend the functionality of Windows Executive. Windowing and graphing system – implements the GUI. USER-MODE PROCESSES 1. Special system processes - user-mode services such as the session manager. 2. Service processes - services used by both Microsoft and other external software developers to extend system functionality 3. Environment subsystems - provide different operating system environments. 4. User applications - These include executable (EXE) programs. Classic UNIX System - called Uniplexed Information and Computing Service (UNICS). 3 Levels of Architecture of a classic UNIX: User level - focuses on the linked programs and libraries. Hardware level - focuses on the physical hardware and interface. System kernel - focuses on the overall operation of the system. Shell – supports system calls from applications. System V Release 4 (SVR4) – joint development by AT&T and Sun Microsystems. Linux Operating System - free open-source variant of the UNIX operating system. 2 VITAL CHARACTERISTICS OF THE LINUX LOADABLE MODULES: 1. Dynamic linking – modules can be loaded and linked into the kernel. 2. Stackable modules – modules are arranged in hierarchical order. Android operating system - Linux-based system originally designed for mobile phones. MODULE 2 Process: - can be a program in execution. - can be an instance of a program running on a computer. - can be considered as an entity that can be assigned to and executed on a processor. - can be treated as a unit of activity that executes a sequence of instructions, a current state, and an associated set of system resources. - can also be defined as an environment that consists of a number of elements for executing a user-level program. Identifier – unique identifier for each process. Process State – current activity of a process. New – process is being created. Ready –process is waiting to be assigned to a processor. Running – instructions are being executed. Waiting – process is waiting for a particular event to occur. Terminated – process has finished the execution. Priority – priority level relative to other processes. Program counter – address of the next instruction to be executed. Memory pointer – pointers to program codes and data. Context data – data present in a processor's registers. I/O status information – different information associated with input/output. Accounting information – different tracking information. Process control block - elements of a process are stored in a data structure. Also called process images. TWO-STATE PROCESS MODEL: 1. Not running state – When OS creates a new process, it creates a process control block for the new process. 2. Running state – Dispatch portion of the OS selects a particular process to run. FIVE-STATE PROCESS MODEL: 1. New state - process that has just been created. 2. Ready state - process is prepared to execute. 3. Running state - process that is currently being executed. 4. Blocked state/Waiting state - process that cannot execute until some event occurs. 5. Exit state - process that has been released, either because it halted or it was terminated. A process can be placed in a suspended state by any of the following: a. The process itself b. A parent process c. The operating system 4 TYPES OF TABLES  1. Memory tables – keep track of both the main and the secondary memory. 2. I/O tables – manage the input and output devices. 3. File tables – hold information regarding the existence of files. 4. Process tables – manage processes. Process Attributes: 1. Process identification – unique numeric identifiers. 2. Processor state information – processor registers' information. 3. Process control information – additional information needed by the OS to control active processes. User mode – the less-privileged mode. Kernel mode – the more-privileged mode. Process Creation - When a new process is to be added. Process Switching - When the operating system controls the currently running processes, a process switch may occur at any time. Process Termination - Any computer system must provide means for a process to indicate its completion.