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Movements, leaders, victories and the continuing fight for equality.
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Wilmington, North Carolina once had a thriving Black middle class and an elected interracial government. In 1898 white supremacists used violence to overthrow that government, kill Black residents and drive many others from the city.
MORE →Reflects the personal views, recollections, and perspective of the author, Mike Davis.
This is a personal recollection on the Move fire on May 13, 1985
| EKA1 | |
|---|---|
| Developer | Psion Symbian Ltd. |
| Written in | Assembly language, C |
| OS family | EPOC (Symbian) |
| Working state | Discontinued |
| Source model | Proprietary |
| Initial release | 1989 |
| Marketing target | PDAs, mobile phones |
| Available in | English |
| Supported platforms | x86, ARM |
| Kernel type | Microkernel |
| Succeeded by | EKA2 |
| Official website | developer |
EKA1 (EPOC Kernel Architecture 1) is the first-generation kernel for the operating system Symbian OS.[1] EKA1 originated in the earlier 32-bit operating system EPOC.[2] It offers preemptive computer multitasking and memory protection, but no real-time computing guarantees, and a single-threaded device driver model.[2][3] EKA1 was replaced by EKA2 as the default kernel starting with Symbian v9.[3]
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.,[3][4] when it was formed to license this kernel and associated operating system to mobile phone makers.[5][6]
{{cite news}}: CS1 maint: deprecated archival service (link)
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 | This operating-system-related article is a stub. You can help Wikipedia by adding missing information. |
Source: Wikipedia. Article content is retrieved live through the MediaWiki API.
EKA1 (EPOC Kernel Architecture 1) is the first-generation kernel for the operating system Symbian OS. EKA1 originated in the earlier 32-bit operating system EPOC. It offers preemptive computer multitasking and memory protection, but no real-time computing guarantees, and a single-threaded device driver model. EKA1 was replaced by EKA2 as the default kernel starting with Symbian v9. 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.
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 8.1, and was superseded in 2005. The main advantage of EKA2 was its ability to run full telephone signalling protocol stacks. Previously, on Symbian phones, these had to run on a separate central processing unit (CPU). Such signalling stacks are very complex and rewriting them to work natively on Symbian OS is typically not an option. EKA2 thus allows personality layers to emulate the basic primitives of other operating systems, thus allowing existing signalling stacks to run largely unchanged. Real-time guarantees are a prerequisite of signalling stacks, and also help with multimedia tasks. However, as with any RTOS, a full analysis of all threads is needed before any real-time guarantees can be offered to anything except the highest-priority thread; because higher priority threads may prevent lower-priority threads from running. Any multimedia task is likely to involve graphics, storage and/or networking activity, all of which are more likely to disrupt the stream than the kernel is. Inside the kernel, EKA1 only allowed one thread (plus a null idle thread). EKA2 allows many threads. This makes it much easier to write device drivers that involve complex finite-state machines, such as those for SD card memory sticks or USB flash drives. Interrupts are handled with an interrupt service routine, which may request an immediate deferred function call (called as soon as the interrupts are processed), or a deferred function call, which is queued to run on a kernel thread. Either may in turn communicate with user-side threads. Power management in EKA2 was largely unchanged from EKA1. The exact scheme varies between phones, but generally the null thread puts the CPU and peripherals to sleep, after having requested a wake-up whenever the next timer is due to expire. EKA2 runs on ARM architecture CPUs and the WINS emulator. Unofficial ports exist for other CPUs. On the emulator, EKA2 provides somewhat better emulation than EKA1, more so for the RProcess APIs which Symbian OS uses to represent processes. In EKA1 they didn't work at all on the emulator, which runs as a single Windows process. Much of the credit for EKA2 goes to a single Symbian kernel engineer, who began the project as an experiment many years before it became an official part of 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 on June 5, 1997 by the Symbian Ltd. consortium. Symbian OS is a descendant of Psion's EPOC, and was mostly used on ARM processors, although an x86 port existed. A modified version of Symbian for x86 was used on the Fujitsu LOOX F-07C where it was dual booted with Windows 7. Symbian was used primarily by Nokia, and in select models of Samsung, Motorola, and Sony Ericsson devices. It was also prevalent in Japan, used 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 in comparison to Windows Mobile and Pocket PC platforms. The Symbian OS platform is formed of two components: one being the microkernel-based operating system with its associated libraries, and the other being the user interface (as middleware), which provides the graphical shell atop the OS. The most prominent user interface was the S60 (formerly Series 60) platform built by Nokia, first released in 2002 and powering most Nokia Symbian devices. UIQ was a competing user interface mostly used by Motorola and Sony Ericsson that focused on pen-based devices, rather than a traditional keyboard interface from S60. Another interface was the MOAP(S) platform from carrier NTT DoCoMo in the Japanese market. Applications for these different interfaces were not compatible with each other, despite each being built atop Symbian OS. Nokia became the largest shareholder of Symbian Ltd. in 2004 and purchased the entire company in 2008. The non-profit Symbian Foundation was then created to make a royalty-free successor to Symbian OS. Seeking to unify the platform, S60 became the Foundation's favoured interface and UIQ stopped development. The touchscreen-focused Symbian^1 (or S60 5th Edition) was created as a result in 2009. Symbian^2 (based on MOAP) was used by NTT DoCoMo, one of the members of the Foundation, for the Japanese market. Symbian^3 was released in 2010 as the successor to S60 5th Edition, by which time it became fully free software. The transition from a proprietary operating system to a free software project is believed to be one of the largest in history. Symbian^3 received the Anna and Belle updates in 2011. The Symbian Foundation disintegrated in late 2010 and Nokia took back control of the OS development. In February 2011, Nokia, by then the only remaining company still supporting Symbian outside Japan, announced that it would use Microsoft's Windows Phone 7 as its primary smartphone platform, while Symbian would be gradually wound down. Two months later, Nokia moved the OS to proprietary licensing, only collaborating with the Japanese OEMs and later outsourced Symbian development to Accenture. Although support was promised until 2016, including two major planned updates, by 2012 Nokia had mostly abandoned development and most Symbian developers had already left Accenture, and in January 2014 Nokia stopped accepting new or changed Symbian software from developers. The Nokia 808 PureView in 2012 was officially the last Symbian smartphone from Nokia. NTT DoCoMo continued releasing OPP(S) (Operator Pack Symbian, successor of MOAP) devices in Japan, which still act as middleware on top of Symbian. Phones running this include the F-07F from Fujitsu and SH-07F from Sharp in 2014.
Before the 1921 destruction of Tulsa’s Greenwood District, Black residents had created a remarkable center of business and community life. The district included stores, professional offices, entertainment venues and homes owned by Black citizens. Understanding Greenwood means learning what was built—not only what was burned.
MORE →Shirley Chisholm, elected in 1968.
