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EKA1
EKA1 (EPOC Kernel Architecture 1) is the first-generation kernel for the operating system Symbian OS. EKA1 originated in the earlier operating system EPOC. It offers preemptive computer multitasking and memory protection, but no real-time computing guarantees, and a single- threaded device driver model. It was largely been superseded by EKA2. Much of EKA1 was developed by a single software engineer, Colly Myers, when he was working for Psion Software in the early 1990s. Myers went on to act as CEO for Symbian Ltd., when it was formed to license this kernel and associated operating system to mobile phone makers. He is now CEO of Issuebits Ltd. See also *Psion (company) Psion PLC was a designer and manufacturer of mobile handheld computers for commercial and industrial uses. The company was headquartered in London, England, with major operations in Mississauga, Ontario, Canada, and other company offices in E ... {{DEFAULTSORT:Eka1 Operating system kernels Symbian OS ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
EKA2
EKA2 (EPOC Kernel Architecture 2) is the second-generation Symbian platform real-time operating system kernel, which originated in the earlier operating system EPOC. EKA2 began with a proprietary software license. In October 2009, it was released as free and open-source software under an Eclipse Public License. In April 2011, it was reverted to a proprietary license. Like its predecessor, EKA1, it has preemptive multithreading and full memory protection. The main differences are: * Real-time guarantees: each application programming interface ( API) call is fast, but more importantly, time-bound * Multiple threads inside the kernel, and outside * Pluggable memory models, allowing better support for later generations of ARM instruction set architecture. * A ''nanokernel'' which provides the most basic OS facilities upon which other ''personality layers'' can be built The user interface of EKA2 is almost fully compatible with EKA1. EKA1 was not used after Symbian OS version 8. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Symbian OS
Symbian is a discontinued mobile operating system (OS) and computing platform designed for smartphones. It was originally developed as a proprietary software OS for personal digital assistants in 1998 by the Symbian Ltd. consortium. Symbian OS is a descendant of Psion's EPOC, and was released exclusively on ARM processors, although an unreleased x86 port existed. Symbian was used by many major mobile phone brands, like Samsung, Motorola, Sony Ericsson, and above all by Nokia. It was also prevalent in Japan by brands including Fujitsu, Sharp and Mitsubishi. As a pioneer that established the smartphone industry, it was the most popular smartphone OS on a worldwide average until the end of 2010, at a time when smartphones were in limited use, when it was overtaken by iOS and Android. It was notably less popular in North America. The Symbian OS platform is formed of two components: one being the microkernel-based operating system with its associated libraries, and the other bei ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Symbian
Symbian is a discontinued mobile operating system (OS) and computing platform designed for smartphones. It was originally developed as a proprietary software OS for personal digital assistants in 1998 by the Symbian Ltd. consortium. Symbian OS is a descendant of Psion's EPOC, and was released exclusively on ARM processors, although an unreleased x86 port existed. Symbian was used by many major mobile phone brands, like Samsung, Motorola, Sony Ericsson, and above all by Nokia. It was also prevalent in Japan by brands including Fujitsu, Sharp and Mitsubishi. As a pioneer that established the smartphone industry, it was the most popular smartphone OS on a worldwide average until the end of 2010, at a time when smartphones were in limited use, when it was overtaken by iOS and Android. It was notably less popular in North America. The Symbian OS platform is formed of two components: one being the microkernel-based operating system with its associated libraries, and the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kernel (operating System)
The kernel is a computer program at the core of a computer's operating system and generally has complete control over everything in the system. It is the portion of the operating system code that is always resident in memory and facilitates interactions between hardware and software components. A full kernel controls all hardware resources (e.g. I/O, memory, cryptography) via device drivers, arbitrates conflicts between processes concerning such resources, and optimizes the utilization of common resources e.g. CPU & cache usage, file systems, and network sockets. On most systems, the kernel is one of the first programs loaded on startup (after the bootloader). It handles the rest of startup as well as memory, peripherals, and input/output (I/O) requests from software, translating them into data-processing instructions for the central processing unit. The critical code of the kernel is usually loaded into a separate area of memory, which is protected from access by application ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Device Driver
In computing, a device driver is a computer program that operates or controls a particular type of device that is attached to a computer or automaton. A driver provides a software interface to hardware devices, enabling operating systems and other computer programs to access hardware functions without needing to know precise details about the hardware being used. A driver communicates with the device through the computer bus or communications subsystem to which the hardware connects. When a calling program invokes a routine in the driver, the driver issues commands to the device (drives it). Once the device sends data back to the driver, the driver may invoke routines in the original calling program. Drivers are hardware dependent and operating-system-specific. They usually provide the interrupt handling required for any necessary asynchronous time-dependent hardware interface. Purpose The main purpose of device drivers is to provide abstraction by acting as a translator b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thread (computing)
In computer science, a thread of execution is the smallest sequence of programmed instructions that can be managed independently by a scheduler, which is typically a part of the operating system. The implementation of threads and processes differs between operating systems. In Modern Operating Systems, Tanenbaum shows that many distinct models of process organization are possible.TANENBAUM, Andrew S. Modern Operating Systems. 1992. Prentice-Hall International Editions, ISBN 0-13-595752-4. In many cases, a thread is a component of a process. The multiple threads of a given process may be executed concurrently (via multithreading capabilities), sharing resources such as memory, while different processes do not share these resources. In particular, the threads of a process share its executable code and the values of its dynamically allocated variables and non- thread-local global variables at any given time. History Threads made an early appearance under the name of "t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Real-time Computing
Real-time computing (RTC) is the computer science term for hardware and software systems subject to a "real-time constraint", for example from event to system response. Real-time programs must guarantee response within specified time constraints, often referred to as "deadlines". Ben-Ari, Mordechai; "Principles of Concurrent and Distributed Programming", ch. 16, Prentice Hall, 1990, , page 164 Real-time responses are often understood to be in the order of milliseconds, and sometimes microseconds. A system not specified as operating in real time cannot usually ''guarantee'' a response within any timeframe, although ''typical'' or ''expected'' response times may be given. Real-time processing ''fails'' if not completed within a specified deadline relative to an event; deadlines must always be met, regardless of system load. A real-time system has been described as one which "controls an environment by receiving data, processing them, and returning the results sufficiently quic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Multitasking
In computing, multitasking is the concurrent execution of multiple tasks (also known as processes) over a certain period of time. New tasks can interrupt already started ones before they finish, instead of waiting for them to end. As a result, a computer executes segments of multiple tasks in an interleaved manner, while the tasks share common processing resources such as central processing units (CPUs) and main memory. Multitasking automatically interrupts the running program, saving its state (partial results, memory contents and computer register contents) and loading the saved state of another program and transferring control to it. This "context switch" may be initiated at fixed time intervals ( pre-emptive multitasking), or the running program may be coded to signal to the supervisory software when it can be interrupted ( cooperative multitasking). Multitasking does not require parallel execution of multiple tasks at exactly the same time; instead, it allows more than o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Preemption (computing)
In computing, preemption is the act of temporarily interrupting an executing task, with the intention of resuming it at a later time. This interrupt is done by an external scheduler with no assistance or cooperation from the task. This preemptive scheduler usually runs in the most privileged protection ring, meaning that interruption and resuming are considered highly secure actions. Such a change in the currently executing task of a processor is known as context switching. User mode and kernel mode In any given system design, some operations performed by the system may not be preemptable. This usually applies to kernel functions and service interrupts which, if not permitted to run to completion, would tend to produce race conditions resulting in deadlock. Barring the scheduler from preempting tasks while they are processing kernel functions simplifies the kernel design at the expense of system responsiveness. The distinction between user mode and kernel mode, which ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Operating System
An operating system (OS) is system software that manages computer hardware, software resources, and provides common daemon (computing), services for computer programs. Time-sharing operating systems scheduler (computing), schedule tasks for efficient use of the system and may also include accounting software for cost allocation of Scheduling (computing), processor time, mass storage, printing, and other resources. For hardware functions such as input and output and memory allocation, the operating system acts as an intermediary between programs and the computer hardware, although the application code is usually executed directly by the hardware and frequently makes system calls to an OS function or is interrupted by it. Operating systems are found on many devices that contain a computer from cellular phones and video game consoles to web servers and supercomputers. The dominant general-purpose personal computer operating system is Microsoft Windows with a market share of aroun ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Psion (company)
Psion PLC was a designer and manufacturer of mobile handheld computers for commercial and industrial uses. The company was headquartered in London, England, with major operations in Mississauga, Ontario, Canada, and other company offices in Europe, the United States, Asia, Latin America, and the Middle East. It was a public company listed on the London Stock Exchange () and was once a constituent of the FTSE 100 Index. Psion's operational business was formed in September 2000 from a merger of Psion and Canadian-based Teklogix Inc., and was a global provider of solutions for mobile computing and wireless data collection. The Group's products and services included rugged mobile hardware, secure software and wireless networks, professional services, and support programs. Psion worked with its clients in the area of burgeoning technologies, including imaging, voice recognition, and radio-frequency identification (RFID). They had operations worldwide in 14 countries, and customer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
