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121-535: The competing layouts devised for French (e.g., the ZHJAY layout put forward in 1907, Claude Marsan's 1976 layout, the 2002 Dvorak -fr, and the 2005 BÉPO layout ) have obtained only limited recognition, although the latter has been included in the 2019 French keyboard layout standard. The AZERTY layout appeared in France in the last decade of the 19th century as a variation on American QWERTY typewriters. Its exact origin

242-541: A BÉPO layout. Initially due in January 2018, the standard was released in April 2019. The layout keeps the same placement for the 26 Latin letters and 10 digits, but moves others (such as some accented letters and punctuation signs), while it adds a range of other symbols (accessible with Shift, AltGr). There is easy access to guillemets « » (French quotes), accented capital letters: À, É, Ç, as well as Œ/œ, Æ/æ, which

363-532: A produces ä . The grave accent can be generated by striking the ` key (in the French AZERTY layout it is located to the right of the ù key) on Macintosh keyboards, while on PC-type keyboards it can be generated by using the combination Alt Gr + è . In the Belgian AZERTY layout, the grave accent is generated by the combination Alt Gr + μ (the μ key is located to

484-402: A respectively, in the fr-oss keyboard layout; their uppercase equivalents can be generated using the same key combinations plus the ⇧ Shift key. Other useful punctuation symbols, such as ≤ , ≥ , or ≠ , can be more easily accessed in the same way. Also called angle quotes, French quotation marks, or double chevrons, these polylines are pointed like arrows ( « or » ), sometimes forming

605-428: A system call to perform a block I/O write operation, then the system call might execute the following instructions: While the writing takes place, the operating system will context switch to other processes as normal. When the device finishes writing, the device will interrupt the currently running process by asserting an interrupt request . The device will also place an integer onto the data bus. Upon accepting

726-527: A Dvorak one without any problems or additional configuration. This eliminates the burden of producing additional keymaps for every variant of QWERTY provided. Runtime layout switching is also possible. ChromeOS and ChromiumOS offer Dvorak, and there are three different ways to switch the keyboard to the Dvorak layout. ChromeOS includes the US Dvorak and UK Dvorak layouts. Apple had Dvorak advocates since

847-434: A complementary set of punctuation marks used as a form of quotation mark. With a US International Keyboard and corresponding layout, Alt Gr + [ and Alt Gr + ] can also be used. The characters are standard on French Canadian keyboards and some others. Macintosh users can type « as ⌥ Option + \ and » as ⌥ Option + ⇧ + \ . (This applies to all English-language keyboard layouts supplied with

968-645: A computer even if they are not compatible with the base operating system. A library operating system (libOS) is one in which the services that a typical operating system provides, such as networking, are provided in the form of libraries and composed with a single application and configuration code to construct a unikernel : a specialized (only the absolute necessary pieces of code are extracted from libraries and bound together ), single address space , machine image that can be deployed to cloud or embedded environments. The operating system code and application code are not executed in separated protection domains (there

1089-585: A development of MULTICS for a single user. Because UNIX's source code was available, it became the basis of other, incompatible operating systems, of which the most successful were AT&T 's System V and the University of California 's Berkeley Software Distribution (BSD). To increase compatibility, the IEEE released the POSIX standard for operating system application programming interfaces (APIs), which

1210-488: A faster and more ergonomic alternative to the QWERTY layout (the de facto standard keyboard layout). Dvorak proponents claim that it requires less finger motion and as a result reduces errors, increases typing speed, reduces repetitive strain injuries , or is simply more comfortable than QWERTY. Dvorak has failed to replace QWERTY as the most common keyboard layout, with the most pointed-to reasons being that QWERTY

1331-538: A few layouts: QWERTY, Dvorak, French ( AZERTY ), and other foreign-language layouts. Since about 1998, beginning with Mac OS 8.6 , Apple has included the Dvorak layout. It can be activated with the Keyboard Control Panel and selecting "Dvorak". The setting is applied once the Control Panel is closed out. Apple also includes a Dvorak variant they call "Dvorak – Qwerty ⌘". With this layout,

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1452-468: A higher learning cost. Apple's keyboards use the same AZERTY layout in both France and Belgium. Based on the Belgian version, the most notable differences are the locations for the @-sign and €-sign, among others. MacOS also supports the standard French layout for non-Apple keyboards; the standard Belgian layout, however, is available through third-party support only. There is an Arabic variant of

1573-533: A keyboard layout that automatically switches to standard (QWERTY) after pressing the two hotkeys (SHIFT and CTRL). Many operating systems based on UNIX , including OpenBSD , FreeBSD , NetBSD , OpenSolaris , Plan 9 , and most Linux distributions , can be configured to use the U.S. Dvorak layout and a handful of variants. Furthermore, all current Unix-like systems with X.Org and appropriate keymaps installed (and virtually all systems meant for desktop use include them) are able to use any QWERTY-labeled keyboard as

1694-484: A large legal settlement was paid. In the twenty-first century, Windows continues to be popular on personal computers but has less market share of servers. UNIX operating systems, especially Linux, are the most popular on enterprise systems and servers but are also used on mobile devices and many other computer systems. On mobile devices, Symbian OS was dominant at first, being usurped by BlackBerry OS (introduced 2002) and iOS for iPhones (from 2007). Later on,

1815-442: A library with no protection between applications, such as eCos . A hypervisor is an operating system that runs a virtual machine . The virtual machine is unaware that it is an application and operates as if it had its own hardware. Virtual machines can be paused, saved, and resumed, making them useful for operating systems research, development, and debugging. They also enhance portability by enabling applications to be run on

1936-447: A malformed machine instruction . However, the most common error conditions are division by zero and accessing an invalid memory address . Users can send messages to the kernel to modify the behavior of a currently running process. For example, in the command-line environment , pressing the interrupt character (usually Control-C ) might terminate the currently running process. To generate software interrupts for x86 CPUs,

2057-523: A national flag that matches the current language, a 'DV' represents Dvorak and a 'DQ' represents Dvorak – Qwerty ⌘) brings up a drop-down menu, allowing the user to choose the desired layout. Subsequent keystrokes will reflect the choice, which can be reversed the same way. Mac OS X 10.5 "Leopard" and later offer a keyboard identifier program that asks users to press a few keys on their keyboards. Dvorak, QWERTY and many national variations of those designs are available. If multiple keyboards are connected to

2178-455: A particular application's memory is stored, or even whether or not it has been allocated yet. In modern operating systems, memory which is accessed less frequently can be temporarily stored on a disk or other media to make that space available for use by other programs. This is called swapping , as an area of memory can be used by multiple programs, and what that memory area contains can be swapped or exchanged on demand. Virtual memory provides

2299-419: A patent in 1932 – most notably in the placement of Z. Today's keyboards have more keys than the original typewriter did, and other significant differences existed: Modern U.S. Dvorak layouts almost always place ; and : together on a single key, and / and ? together on a single key. Thus, if the keycaps of a modern keyboard are rearranged so that the unshifted symbol characters match

2420-651: A plain US-QWERTY keyboard, being an extension of it. However, only AZERTY is widely sold in French shops. Another alternative is the BÉPO layout, a French-language application of Dvorak’s principles for ergonomic typing . As of 2024, only a few specialized manufacturers sell keyboards with the BÉPO layout printed on it; however, its practitioners use to type blindly, without looking at the keys , for increased efficiency, if at

2541-503: A program does not interfere with memory already in use by another program. Since programs time share, each program must have independent access to memory. Cooperative memory management, used by many early operating systems, assumes that all programs make voluntary use of the kernel 's memory manager, and do not exceed their allocated memory. This system of memory management is almost never seen any more, since programs often contain bugs which can cause them to exceed their allocated memory. If

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2662-408: A program fails, it may cause memory used by one or more other programs to be affected or overwritten. Malicious programs or viruses may purposefully alter another program's memory, or may affect the operation of the operating system itself. With cooperative memory management, it takes only one misbehaved program to crash the system. Memory protection enables the kernel to limit a process' access to

2783-440: A program tries to access memory that is not accessible memory, but nonetheless has been allocated to it, the kernel is interrupted (see § Memory management ) . This kind of interrupt is typically a page fault . When the kernel detects a page fault it generally adjusts the virtual memory range of the program which triggered it, granting it access to the memory requested. This gives the kernel discretionary power over where

2904-470: A significant amount of CPU time. Direct memory access (DMA) is an architecture feature to allow devices to bypass the CPU and access main memory directly. (Separate from the architecture, a device may perform direct memory access to and from main memory either directly or via a bus.) When a computer user types a key on the keyboard, typically the character appears immediately on the screen. Likewise, when

3025-517: A single finger to jump directly from one row, over the home row to another row (e.g., typing "minimum" [which often comes out as "minimun" or "mimimum"] on the QWERTY keyboard). In the English language, there are about 1,200 words that require a hurdle on the QWERTY layout. In contrast, there are only a few words requiring a hurdle on the Dvorak layout (e.g. "spiky", where the "piky" is typed entirely on

3146-632: A space, in a word-processing package such as OpenOffice.org Writer , or by using Ctrl + ⇧ + Espace [Spacebar] in Microsoft Word. Apart from these gaps, the French AZERTY layout has some strange features which are still present in the Microsoft Windows Vista operating system: In January 2016, the French Ministry of Culture , which is in charge of language affairs, expressed a will to offer an alternative to

3267-402: A specific moment in time. Hard real-time systems require exact timing and are common in manufacturing , avionics , military, and other similar uses. With soft real-time systems, the occasional missed event is acceptable; this category often includes audio or multimedia systems, as well as smartphones. In order for hard real-time systems be sufficiently exact in their timing, often they are just

3388-455: A standard for the Dvorak layout known as ANSI X4.22-1983. This standard gave the Dvorak layout official recognition as an alternative to the QWERTY keyboard. The layout standardized by the ANSI differs from the original or "classic" layout devised and promulgated by Dvorak. Indeed, the layout promulgated publicly by Dvorak differed slightly from the layout for which Dvorak & Dealey applied for

3509-476: A strictly better coverage of French spelling than the various variants of AZERTY (as available in Windows): indeed, it supports all diacritics of French (acute accent, grave accent, circumflex, diaeresis) as dead keys (allowing for those diacritics on both lowercase and uppercase letters), it has a separate key for “ç” (allowing it to be uppercased) and it even features the French guillemets “«»”; however, it lacks

3630-514: A switch, the user could switch from one layout to the other. This modification was entirely unofficial but was inadvertently demonstrated at the 1984 Comdex show, in Las Vegas , by an Apple employee whose mission was to demonstrate Apple Logo II. The employee had become accustomed to the Dvorak layout and brought the necessary parts to the show, installed them in a demo machine, then did his Logo demo. Viewers, curious that he always reached behind

3751-417: A user moves a mouse , the cursor immediately moves across the screen. Each keystroke and mouse movement generates an interrupt called Interrupt-driven I/O . An interrupt-driven I/O occurs when a process causes an interrupt for every character or word transmitted. Devices such as hard disk drives , solid-state drives , and magnetic tape drives can transfer data at a rate high enough that interrupting

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3872-453: A variation of the classic reader/writer problem . The writer receives a pipe from the shell for its output to be sent to the reader's input stream. The command-line syntax is alpha | bravo . alpha will write to the pipe when its computation is ready and then sleep in the wait queue. bravo will then be moved to the ready queue and soon will read from its input stream. The kernel will generate software interrupts to coordinate

3993-562: Is remote direct memory access , which enables each CPU to access memory belonging to other CPUs. Multicomputer operating systems often support remote procedure calls where a CPU can call a procedure on another CPU, or distributed shared memory , in which the operating system uses virtualization to generate shared memory that does not physically exist. A distributed system is a group of distinct, networked computers—each of which might have their own operating system and file system. Unlike multicomputers, they may be dispersed anywhere in

4114-489: Is 1.4 ) that allows anyone to easily create any keyboard layout desired, thus allowing the creation and installation of any international Dvorak keyboard layout such as Dvorak Type II (for German), Svorak (for Swedish) etc. Another advantage of the Microsoft Keyboard Layout Creator with respect to third-party programs for installing an international Dvorak layout is that it allows creation of

4235-484: Is a change away from the currently running process. Similarly, both hardware and software interrupts execute an interrupt service routine . Software interrupts may be normally occurring events. It is expected that a time slice will occur, so the kernel will have to perform a context switch . A computer program may set a timer to go off after a few seconds in case too much data causes an algorithm to take too long. Software interrupts may be error conditions, such as

4356-587: Is because Belgium is predominantly bilingual (French-Dutch) and officially trilingual (a third language, German, is spoken in the East Cantons). The key to the right of 0 on the numeric keypad corresponds either to the full stop or to the comma (which is why there are two distinct keyboard drivers under Windows). The AZERTY keyboard as used in Flanders , the Dutch-speaking part of Belgium, uses

4477-422: Is difficult to define, but has been called "the layer of software that manages a computer's resources for its users and their applications ". Operating systems include the software that is always running, called a kernel —but can include other software as well. The two other types of programs that can run on a computer are system programs —which are associated with the operating system, but may not be part of

4598-443: Is only a single application running, at least conceptually, so there is no need to prevent interference between applications) and OS services are accessed via simple library calls (potentially inlining them based on compiler thresholds), without the usual overhead of context switches , in a way similarly to embedded and real-time OSes. Note that this overhead is not negligible: to the direct cost of mode switching it's necessary to add

4719-648: Is only a small part of the complicated physical activity of typing. The work of Dvorak paved the way for other optimized keyboard layouts for English such as Colemak , but also for other languages such as the German Neo and the French BÉPO . Over the decades, symbol keys were shifted around the keyboard resulting in variations of the Dvorak design. In 1982, the American National Standards Institute (ANSI) implemented

4840-499: Is supported by most UNIX systems. MINIX was a stripped-down version of UNIX, developed in 1987 for educational uses, that inspired the commercially available, free software Linux . Since 2008, MINIX is used in controllers of most Intel microchips , while Linux is widespread in data centers and Android smartphones. The invention of large scale integration enabled the production of personal computers (initially called microcomputers ) from around 1980. For around five years,

4961-473: Is that they do not load user-installed software. Consequently, they do not need protection between different applications, enabling simpler designs. Very small operating systems might run in less than 10 kilobytes , and the smallest are for smart cards . Examples include Embedded Linux , QNX , VxWorks , and the extra-small systems RIOT and TinyOS . A real-time operating system is an operating system that guarantees to process events or data by or at

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5082-435: Is the part of the operating system that provides protection between different applications and users. This protection is key to improving reliability by keeping errors isolated to one program, as well as security by limiting the power of malicious software and protecting private data, and ensuring that one program cannot monopolize the computer's resources. Most operating systems have two modes of operation: in user mode ,

5203-530: Is unknown. At the start of the 20th century, the French ZHJAYS layout, created by Albert Navarre, failed to break into the market partly because secretaries were already accustomed to the AZERTY layout and partly because it differed more from the QWERTY layout than the AZERTY layout did. In France, the AZERTY layout is the de facto norm for keyboards. In 1976, a QWERTY layout adapted to the French language

5324-575: The N key. In the Belgian AZERTY layout, ñ can be generated by a combination of Alt Gr + = . With some operating systems , the Alt key generates characters by means of their individual codes. In order to obtain characters, the Alt key must be pressed and held down while typing the relevant code into the numeric keypad . On Linux , the Alt key gives direct access to French-language special characters. The ligatures œ and æ can be keyed in by using Alt Gr + o and Alt Gr +

5445-410: The ^ key (located to the right of P in most AZERTY layouts), then the vowel requiring the accent (with the exception of y). For example, pressing ^ then a produces â . A diaresis can be generated by striking the ¨ key (in most AZERTY layouts, it is generated by combining the ⇧ + ^ keys), then the vowel requiring the accent. For example, pressing ⇧ + ^ then

5566-542: The CP/M (Control Program for Microcomputers) was the most popular operating system for microcomputers. Later, IBM bought the DOS (Disk Operating System) from Microsoft . After modifications requested by IBM, the resulting system was called MS-DOS (MicroSoft Disk Operating System) and was widely used on IBM microcomputers. Later versions increased their sophistication, in part by borrowing features from UNIX. Apple 's Macintosh

5687-504: The INT assembly language instruction is available. The syntax is INT X , where X is the offset number (in hexadecimal format) to the interrupt vector table . To generate software interrupts in Unix-like operating systems, the kill(pid,signum) system call will send a signal to another process. pid is the process identifier of the receiving process. signum is

5808-580: The X Window System , creation of the guillemet depends on a number of factors including the keyboard layout that is in effect. For example, with the US International Keyboard layout selected, a user would type Alt Gr + [ for « and Alt Gr + ] for » . On some configurations they can be generated by typing « as Alt Gr + z and » as Alt Gr + x . With the compose key, press Compose + < + < and Compose + > + > . Additionally with

5929-498: The personal computer market, as of September 2024 , Microsoft Windows holds a dominant market share of around 73%. macOS by Apple Inc. is in second place (15%), Linux is in third place (5%), and ChromeOS is in fourth place (2%). In the mobile sector (including smartphones and tablets ), as of September 2023 , Android's share is 68.92%, followed by Apple's iOS and iPadOS with 30.42%, and other operating systems with .66%. Linux distributions are dominant in

6050-420: The transistor in the mid-1950s, mainframes began to be built. These still needed professional operators who manually do what a modern operating system would do, such as scheduling programs to run, but mainframes still had rudimentary operating systems such as Fortran Monitor System (FMS) and IBSYS . In the 1960s, IBM introduced the first series of intercompatible computers ( System/360 ). All of them ran

6171-410: The " ASDF " and " JKL; " keys). The row containing said keys is called the home row. The more strokes there are in the home row, the less movement the fingers must do, thus allowing a typist to type faster, more accurately, and with less strain to the hand and fingers. According to letter frequency analysis, the majority of the Dvorak layout's key strokes (70%) are done in the home row, claimed to be

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6292-682: The AZERTY keyboard. It is especially used in the African countries Algeria , Chad , Comoros , Djibouti , Mauritania , Morocco , Tunisia and in Arab communities in French-speaking countries to be able to type both in Arabic and in French. Dvorak Simplified Keyboard Dvorak / ˈ d v ɔːr æ k / is a keyboard layout for English patented in 1936 by August Dvorak and his brother-in-law, William Dealey, as

6413-458: The AZERTY layouts traditionally proposed by the industry. The new layout would have to provide full coverage of the symbols required by French spelling (including accented capitals such as É) as well as other languages of France and European languages written with the Latin alphabet. The project, led by the French national organization for standardization AFNOR , released both this improved AZERTY and

6534-479: The Belgian AZERTY layout, a vowel with an acute accent can be generated by a combination of Alt Gr + ù , then the vowel. The acute accent is not available in the French layout on Windows. The tilde is available under Windows by using a combination of the Alt Gr + é keys, followed by the letter requiring the tilde. On Macs, the ñ can be obtained by the combination of Alt Gr + N keys, followed by

6655-410: The CPU for every byte or word transferred, and having the CPU transfer the byte or word between the device and memory, would require too much CPU time. Data is, instead, transferred between the device and memory independently of the CPU by hardware such as a channel or a direct memory access controller; an interrupt is delivered only when all the data is transferred. If a computer program executes

6776-474: The CPU to re-enter supervisor mode , placing the kernel in charge. This is called a segmentation violation or Seg-V for short, and since it is both difficult to assign a meaningful result to such an operation, and because it is usually a sign of a misbehaving program, the kernel generally resorts to terminating the offending program, and reports the error. Windows versions 3.1 through ME had some level of memory protection, but programs could easily circumvent

6897-475: The Dvorak keyboard mapping , though it was purportedly available through undocumented interfaces. In the early days, Macintosh users could only use the Dvorak layout by editing the "System" file using Apple's "RESource EDITor" ResEdit  – which allowed users to create and edit keyboard layouts, icons, and other interface components. By 1994, a package named 'Electric Dvorak' by John Rethorst provided an easily user-installable "implementation [that]

7018-583: The Dvorak keyboard layout increased by the early 1950s. Numerous businesses and government organizations began to consider retraining their typists on Dvorak keyboards. In this environment, the General Services Administration commissioned Earle Strong to determine whether the switch from QWERTY to Dvorak should be made. After retraining a selection of typists from QWERTY to Dvorak, once the Dvorak group had regained their previous typing speed (which took 100 hours of training, more than

7139-543: The French language. One can also use WinCompose in order to easily type all characters. The character Ç could be typed by pressing ⎄ Compose   ,   C or the character « with ⎄ Compose   <   < , and there is also an option to allow typing accentuated capitals with ⇪ Caps Lock such that Ç can be typed with ⇪ Caps Lock   ç . Some word-processing software packages address some of these gaps. The non-breaking space can be obtained by pressing Ctrl followed by

7260-528: The QWERTY layout by alleviating some of its perceived shortcomings, such as: August Dvorak studied letter frequencies and the physiology of the hand and created a new layout to alleviate the above problems, based on the following principles: The Dvorak layout is intended for the English language. For other European languages, letter frequencies, letter sequences, and bigrams differ from those of English. Also, many languages have letters that do not occur in English. For non-English use, these differences lessen

7381-581: The QWERTY layout needed to be replaced, as QWERTY had not been laid out with the pure intention of ease and speed. Dvorak was joined by his brother-in-law William Dealey, a professor of education at the then North Texas State Teacher's College in Denton, Texas . Dvorak and Dealey's objective was to scientifically design a keyboard to decrease typing errors, speed up typing, and lessen typist fatigue. They engaged in extensive research while designing their keyboard layout. In 1914 and 1915, Dealey attended seminars on

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7502-684: The Workbench disk or installing the system to a hard drive, Dvorak was usable for Workbench application programs. Versions of Microsoft Windows including Windows 95 , Windows NT 3.51 and later have shipped with U.S. Dvorak layout capability. Free updates to use the layout on earlier Windows versions are available for download from Microsoft. Earlier versions, such as DOS 6.2 / Windows 3.1 , included four keyboard layouts: QWERTY, two-handed Dvorak, right-hand Dvorak, and left-hand Dvorak. In May 2004, Microsoft published an improved version of its Keyboard Layout Creator (MSKLC version 1.3 – current version

7623-608: The alleged advantages of the original Dvorak keyboard. However, the Dvorak principles have been applied to the design of keyboards for other languages, though the primary keyboards used by most countries are based on the QWERTY design. The layout was completed in 1932 and granted U.S. patent 2,040,248 in 1936. The American National Standards Institute (ANSI) designated the Dvorak keyboard as an alternative standard keyboard layout in 1982 (INCITS 207-1991 R2007; previously X4.22-1983, X3.207:1991), "Alternate Keyboard Arrangement for Alphanumeric Machines". The original ANSI Dvorak layout

7744-538: The application program, which then interacts with the user and with hardware devices. However, in some systems an application can request that the operating system execute another application within the same process, either as a subroutine or in a separate thread, e.g., the LINK and ATTACH facilities of OS/360 and successors . An interrupt (also known as an abort , exception , fault , signal , or trap ) provides an efficient way for most operating systems to react to

7865-399: The application. Occasionally, stickers were provided to place over the keys for these layouts. However, IBM-compatible PCs used an active, "smart" keyboard. Striking a key generated a key "code", which was sent to the computer. Thus, changing to an alternative keyboard layout was accomplished most easily by simply buying a keyboard with the new layout. Because the key codes were generated by

7986-501: The classic Dvorak layout then the result is the ANSI Dvorak layout. Dvorak is included with all major operating systems (such as Windows , macOS , Linux and BSD ). Although some word processors could simulate alternative keyboard layouts by software, this was application specific; if more than one program was commonly used (e.g., a word processor and a spreadsheet ), the user could be forced to switch layouts depending on

8107-426: The company's early (pre- IPO ) days. Several engineers devised hardware and software to remap the keyboard, which were used inside the company and even sold commercially. The Apple IIe had a keyboard ROM that translated keystrokes into characters. The ROM contained both QWERTY and Dvorak layouts, but the QWERTY layout was enabled by default. A modification could be made and was reversible and did no damage. By flipping

8228-453: The computer's memory. Various methods of memory protection exist, including memory segmentation and paging . All methods require some level of hardware support (such as the 80286 MMU), which does not exist in all computers. In both segmentation and paging, certain protected mode registers specify to the CPU what memory address it should allow a running program to access. Attempts to access other addresses trigger an interrupt, which causes

8349-471: The details of how interrupt service routines behave vary from operating system to operating system. However, several interrupt functions are common. The architecture and operating system must: A software interrupt is a message to a process that an event has occurred. This contrasts with a hardware interrupt — which is a message to the central processing unit (CPU) that an event has occurred. Software interrupts are similar to hardware interrupts — there

8470-399: The easiest row to type because the fingers rest there. Additionally, the Dvorak layout requires the fewest strokes on the bottom row (the most difficult row to type). By contrast, QWERTY requires typists to move their fingers to the top row for a majority of strokes and has only 32% of the strokes done in the home row. Because the Dvorak layout concentrates the vast majority of key strokes to

8591-422: The environment. Interrupts cause the central processing unit (CPU) to have a control flow change away from the currently running program to an interrupt handler , also known as an interrupt service routine (ISR). An interrupt service routine may cause the central processing unit (CPU) to have a context switch . The details of how a computer processes an interrupt vary from architecture to architecture, and

8712-565: The grapheme “œ/Œ”, and lowercase accented letters of French are more cumbersome to type since they require pressing a dead key. The “US-International” QWERTY layout supports French to the same extent than the Portugal’s layout does (diacritics as dead keys, French guillemets, but no “œ/Œ”). Some programmers prefer it over AZERTY, as it is closer to an international standard and allows easier input of ASCII punctuation characters which are used pervasively in programming languages . It can be used on

8833-410: The hardware checks that the software is only executing legal instructions, whereas the kernel has unrestricted powers and is not subject to these checks. The kernel also manages memory for other processes and controls access to input/output devices. The operating system provides an interface between an application program and the computer hardware, so that an application program can interact with

8954-493: The hardware only by obeying rules and procedures programmed into the operating system. The operating system is also a set of services which simplify development and execution of application programs. Executing an application program typically involves the creation of a process by the operating system kernel , which assigns memory space and other resources, establishes a priority for the process in multi-tasking systems, loads program binary code into memory, and initiates execution of

9075-512: The home row, the Dvorak layout uses about 63% of the finger motion required by QWERTY, which is claimed to make the keyboard more ergonomic. Because the Dvorak layout requires less finger motion from the typist compared to QWERTY, some users with repetitive strain injuries have reported that switching from QWERTY to Dvorak alleviated or even eliminated their repetitive strain injuries; however, no scientific study has been conducted verifying this. The typing loads between hands differs for each of

9196-453: The ibus input method framework enabled, users may enter these characters into those applications that accept it by using Ctrl + ⇧ Shift + U followed by their Unicode code points: either A B or B B , respectively. In Microsoft Office applications, typing the US quotation mark (on the 3 key) will produce either a left guillemet « or right guillemet » based on

9317-418: The indirect pollution of important processor structures (like CPU caches , the instruction pipeline , and so on) which affects both user-mode and kernel-mode performance. The first computers in the late 1940s and 1950s were directly programmed either with plugboards or with machine code inputted on media such as punch cards , without programming languages or operating systems. After the introduction of

9438-404: The interrupt request, the operating system will: When the writing process has its time slice expired, the operating system will: With the program counter now reset, the interrupted process will resume its time slice. Among other things, a multiprogramming operating system kernel must be responsible for managing all system memory which is currently in use by the programs. This ensures that

9559-412: The introduction of iOS 8 in 2014, Apple iPhone and iPad users have been able to install third party keyboards on their touchscreen devices which allow for alternative keyboard layouts such as Dvorak on a system wide basis. Starting with iOS 16, the Dvorak keyboard became available as an included system wide keyboard. Apple iOS 4.0 and later supported external Dvorak keyboards. iOS 8.0 and later had

9680-431: The kernel—and applications—all other software. There are three main purposes that an operating system fulfills: With multiprocessors multiple CPUs share memory. A multicomputer or cluster computer has multiple CPUs, each of which has its own memory . Multicomputers were developed because large multiprocessors are difficult to engineer and prohibitively expensive; they are universal in cloud computing because of

9801-452: The key in question sometimes generates the desired symbol directly, but that at least one of the symbols represented on the key will only appear after a second key has been pressed. In order to obtain a symbol in isolation, the space bar must be pressed, otherwise a vowel should be pressed to generate the desired accented form. The other keys are identical, even though traditionally the names of special keys are printed on them in English. This

9922-408: The keyboard itself, all software would respond accordingly. In the mid to late 1980s, a small industry for replacement PC keyboards developed; although most of these were concerned with keyboard "feel" and/or programmable macros , there were several with alternative layouts, such as Dvorak. Amiga operating systems from the 1986 version 1.2 onward allow the user to modify the keyboard layout by using

10043-466: The keyboard layouts. On QWERTY keyboards, 56% of the typing strokes are done by the left hand. As the right hand is dominant for the majority of people, the Dvorak keyboard puts the more often used keys on the right hand side, thereby having 56% of the typing strokes done by the right hand. Awkward strokes are undesirable because they slow down typing, increase typing errors, and increase finger strain. The term hurdling refers to an awkward stroke requiring

10164-456: The keyboard temporarily becomes QWERTY when the Command (⌘/Apple) key is held down. By keeping familiar keyboard shortcuts like "close" or "copy" on the same keys as ordinary QWERTY, this lets some people use their well-practiced muscle memory and may make the transition easier. Mac OS and subsequently Mac OS X allow additional "on-the-fly" switching between layouts: a menu-bar icon (by default,

10285-477: The layout and various other resources. The Belgian AZERTY keyboard allows for the placing of accents on vowels without recourse to encoding via the Alt key + code. This is made possible by the provision of dead keys for each type of accent: ^ ¨ ´ ` (the last two being generated by a combination of Alt Gr + ù and μ respectively). To recap the list of different keys from left to right and from top to bottom: The description partially dead means that pressing

10406-458: The layout). The acute accent is available under Windows by the use of Alt + a , then the vowel requiring the accent. The é combination can be generated using its own key. For Linux users, it can be generated using ⇪ Caps Lock + é then the vowel. On a Macintosh AZERTY keyboard, the acute accent is generated by a combination of the Alt + ⇧ + & , keys, followed by the vowel. In

10527-553: The left pointer finger; it corresponds to ";rgvt" on QWERTY). Operating system An operating system ( OS ) is system software that manages computer hardware and software resources, and provides common services for computer programs . Time-sharing operating systems schedule tasks for efficient use of the system and may also include accounting software for cost allocation of processor time , mass storage , peripherals, and other resources. For hardware functions such as input and output and memory allocation ,

10648-537: The letters DHIATENSOR for the home row. Blickensderfer had determined that 85% of English words contained these letters. The Dvorak keyboard uses the same letters in its home row, apart from replacing R with U , and even keeps the consonants in the same order, but moves the vowels to the left: AOEUIDHTNS . In 1933, Dvorak started entering typists trained on his keyboard into the International Commercial Schools Contest, which

10769-504: The machine before and after allowing other people to type, asked him about the modification. He spent as much time explaining the Dvorak keyboard as explaining Logo. Apple brought new interest to the Dvorak layout with the Apple IIc , which had a mechanical switch above the keyboard whereby the user could switch back and forth between the QWERTY and Dvorak. The IIc Dvorak layout was even mentioned by 1984 advertisements, which stated that

10890-400: The memory allocated to a different one. Around the same time, teleprinters began to be used as terminals so multiple users could access the computer simultaneously. The operating system MULTICS was intended to allow hundreds of users to access a large computer. Despite its limited adoption, it can be considered the precursor to cloud computing . The UNIX operating system originated as

11011-466: The name shift instead of maj and caps lock instead of verr maj . The AZERTY layout is used in France , Belgium and some African countries. It differs from the QWERTY layout thus: The French and Belgian AZERTY keyboards also have special characters used in the French and Dutch language, such as é, è, ê, ï, ë, ... and other characters such as &, ", ', and ç (only for French), some located under

11132-408: The need to use it. A general protection fault would be produced, indicating a segmentation violation had occurred; however, the system would often crash anyway. The use of virtual memory addressing (such as paging or segmentation) means that the kernel can choose what memory each program may use at any given time, allowing the operating system to use the same memory locations for multiple tasks. If

11253-539: The numbers and some with combinations of keys. French-speaking people in the Canada use the Canadian Multilingual standard keyboard . It is the only keyboard layout provided by Microsoft Windows that allows to type the grapheme “ Œ/œ ”, needed by French spelling. Although there is no evidence of usage in French-speaking countries, it can be noticed that the keyboard layout of Portugal (QWERTY-based) has

11374-408: The open-source Android operating system (introduced 2008), with a Linux kernel and a C library ( Bionic ) partially based on BSD code, became most popular. The components of an operating system are designed to ensure that various parts of a computer function cohesively. With the de facto obsoletion of DOS , all user software must interact with the operating system to access hardware. The kernel

11495-420: 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 . In

11616-429: The operating system, e.g. "Australian", "British", "Canadian", "Irish", "Irish Extended", "U.S." and "U.S. Extended". Other language layouts may differ.) In French-language keyboard layouts ⌥ Option + 7 and ⌥ Option + ⇧ + 7 can be used. On Nordic keyboards, ⌥ Option + ⇧ + v can be used for « , and ⌥ Option + ⇧ + b can be used for » . For users of Unix-like operating systems running

11737-558: The option to install onscreen keyboards from the App Store, which includes several free and paid Dvorak layouts. Apple added native support for the Dvorak keyboard with the release of iOS 16 in September 2022. Google's Android OS touchscreen keyboard can use Dvorak and other nonstandard layouts natively as of version 4.1. The traditional method for touch typing requires typists to rest their fingers in home position (on QWERTY,

11858-421: The piping. Signals may be classified into 7 categories. The categories are: Input/output (I/O) devices are slower than the CPU. Therefore, it would slow down the computer if the CPU had to wait for each I/O to finish. Instead, a computer may implement interrupts for I/O completion, avoiding the need for polling or busy waiting. Some computers require an interrupt for each character or word, costing

11979-644: The previous apparent benefits of Dvorak to improper experimental design and outright bias on the part of Dvorak, who had designed and directed the previous studies. However, Strong had a personal grudge against Dvorak and had made public statements before his study opposing new keyboard designs. After this study, interest in the Dvorak keyboard waned. Later experiments have shown that many keyboard designs, including some alphabetical ones, allow very similar typing speeds to QWERTY and Dvorak when typists have been trained for them, suggesting that Dvorak's careful design principles may have had little effect because keyboard layout

12100-510: The right of the ù key on Belgian AZERTY keyboards), and then the key for the vowel requiring the accent. The grave-accented letters à , è , and ù (as well as the acute-accented é ), which are part of French orthography, have their own separate keys. Dead-grave and dead-acute (and dead-tilde) would mostly be reserved to "foreign" letters such as Italian ò , Spanish á , í , ó , ú , and ñ , Portuguese ã and õ , etc., or for accented capital letters (which are not present precomposed in

12221-691: The same Mac computer, they can be configured to different layouts and use simultaneously. However should the computer shut down (lack of battery, etc.) the computer will revert to QWERTY for reboot, regardless of what layout the Admin was using. Most mobile phones have software implementations of keyboards on a touch screen. Sometimes the keyboard layout can be changed by means of a freeware third-party utility, such as Hacker's Keyboard for Android , AE Keyboard Mapper for Windows Mobile , or KeybLayout for Symbian OS . The RIM BlackBerry lines offer only QWERTY and its localized variants AZERTY and QWERTZ . Since

12342-418: The same operating system— OS/360 —which consisted of millions of lines of assembly language that had thousands of bugs . The OS/360 also was the first popular operating system to support multiprogramming , such that the CPU could be put to use on one job while another was waiting on input/output (I/O). Holding multiple jobs in memory necessitated memory partitioning and safeguards against one job accessing

12463-566: The science of motion and later reviewed slow-motion films of typists with Dvorak. Dvorak and Dealey meticulously studied the English language, researching the most used letters and letter combinations. They also studied the physiology of the hand. The result in 1932 was the Dvorak Simplified Keyboard. In 1893, George Blickensderfer had developed a keyboard layout for the Blickensderfer typewriter model 5 that used

12584-619: The server and supercomputing sectors. Other specialized classes of operating systems (special-purpose operating systems), such as embedded and real-time systems, exist for many applications. Security-focused operating systems also exist. Some operating systems have low system requirements (e.g. light-weight Linux distribution ). Others may have higher system requirements. Some operating systems require installation or may come pre-installed with purchased computers ( OEM -installation), whereas others may run directly from media (i.e. live CD ) or flash memory (i.e. USB stick). An operating system

12705-408: The setmap command line utility with "usa2" as an argument, or later in 3.x systems by opening the keyboard input preference widget and selecting "Dvorak". Amiga systems versions 1.2 and 1.3 came with the Dvorak keymap on the Workbench disk. Versions 2.x came with the keymaps available on the "Extras" disk. In 3.0 and 3.1 systems, the keymaps were on the "Storage" disk. By copying the respective keymap to

12826-400: The signal number (in mnemonic format) to be sent. (The abrasive name of kill was chosen because early implementations only terminated the process.) In Unix-like operating systems, signals inform processes of the occurrence of asynchronous events. To communicate asynchronously, interrupts are required. One reason a process needs to asynchronously communicate to another process solves

12947-400: The size of the machine needed. The different CPUs often need to send and receive messages to each other; to ensure good performance, the operating systems for these machines need to minimize this copying of packets . Newer systems are often multiqueue —separating groups of users into separate queues —to reduce the need for packet copying and support more concurrent users. Another technique

13068-432: The spacing. In X11, the window system common to many flavors of UNIX, the keyboard interface is completely configurable, allowing each user to assign different functions to each key in line with their personal preferences. For example, specific combinations of Alt Gr key could be assigned to many other characters. It is possible to fill in these gaps by installing a keyboard driver that has been specially enriched for

13189-689: The team directed by Dvorak or by ANSI . These variations have been collectively or individually termed the Dvorak Simplified Keyboard , the American Simplified Keyboard or simply the Simplified Keyboard , but they all have come to be known commonly as the Dvorak keyboard or Dvorak layout . Dvorak was designed with the belief that it would significantly increase typing speeds with respect to

13310-476: The time it took to learn QWERTY. When a new school board was elected, however, it chose to terminate the Dvorak classes. During World War II, while in the Navy, Dvorak conducted experiments which he claimed showed that typists could be retrained to Dvorak in a mere 10 days, though he discarded at least two previous studies which were conducted and whose results are unknown. With such great apparent gains, interest in

13431-494: The world's fastest typist, Barbara Blackburn , had set a record on an Apple IIc with the Dvorak layout. Dvorak was also selectable using the built-in control panel applet on the Apple II GS . The Apple III used a keyboard-layout file loaded from a floppy disk: the standard system-software package included QWERTY and Dvorak layout files. Changing layouts required restarting the machine. The Apple Lisa did not offer

13552-473: The world. Middleware , an additional software layer between the operating system and applications, is often used to improve consistency. Although it functions similarly to an operating system, it is not a true operating system. Embedded operating systems are designed to be used in embedded computer systems , whether they are internet of things objects or not connected to a network. Embedded systems include many household appliances. The distinguishing factor

13673-567: Was a typing contest sponsored by typewriter manufacturers consisting of a series of professional and amateur contests. The professional contests had typists sponsored by typewriter companies to advertise their machines. In the 1930s, the Tacoma, Washington, school district ran an experimental program in typing designed by Dvorak to determine whether to hold Dvorak layout classes. The experiment put 2,700 high school students through Dvorak typing classes and found that students learned Dvorak in one-third

13794-487: Was available as a factory-supplied option on the original IBM Selectric typewriter . August Dvorak was an educational psychologist and professor of education at the University of Washington in Seattle . Touch typing had come into wide use by that time and Dvorak became interested in the layout while serving as an advisor to Gertrude Ford, who was writing her master's thesis on typing errors. He quickly concluded that

13915-450: Was claimed in Dvorak's Navy test), Strong took a second group of QWERTY typists chosen for equal ability to the Dvorak group and retrained them in QWERTY in order to improve their speed at the same time the Dvorak typists were training. The carefully controlled study failed to show any benefit to the Dvorak keyboard layout in typing or training speed. Strong recommended speed training with QWERTY rather than switching keyboards, and attributed

14036-407: Was not possible before on basic AZERTY (Windows' AZERTY); previously alt codes were required. It allows typing words in many languages using dead keys , which are in blue on the picture, to access a variety of diacritics. A few mathematics symbols have also been added. A website for the new AZERTY layout has been created, offering information, visuals of the changes, links to drivers to install

14157-421: Was particularly good on pre-system 7 Macs" as freeware, and especially useful for Mac+ and Mac SE machines running MacOS 6 and 7. Another third-party developer offered a utility program called MacKeymeleon, which put a menu on the menu bar that allowed on-the-fly switching of keyboard layouts. Eventually, Apple Macintosh engineers built the functionality of this utility into the standard system software, along with

14278-445: Was popularized 60 years prior to Dvorak's creation, and that Dvorak's advantages are debated and relatively small. However, most major modern operating systems (such as Windows , macOS , Linux , iOS , Android , ChromeOS , and BSD ) allow a user to switch to the Dvorak layout. The layout can be chosen for use with any hardware keyboard, regardless of any characters printed on the key caps. Several modifications were designed by

14399-510: Was published by the French national organization for standardization in 2019. The AZERTY layout is used on Belgian keyboards, although some non-alphabetic symbols are positioned differently. There are two key details: A dead key serves to modify the appearance of the next character to be typed on the keyboard. Dead keys are mainly used to generate accents (or diacritics ) on vowels . A circumflex accent can be generated by first striking

14520-489: Was put forward, as an experimental standard (NF XP E55-060) by AFNOR. This standard made provision for a temporary adaptation period during which the letters A, Q, Z and W could be positioned as in the traditional AZERTY layout. In January 2016, the French Culture Ministry has looked to replace the industrial AZERTY layouts with one that will allow a better typing of French and other languages. A standard

14641-406: Was the first popular computer to use a graphical user interface (GUI). The GUI proved much more user friendly than the text-only command-line interface earlier operating systems had used. Following the success of Macintosh, MS-DOS was updated with a GUI overlay called Windows . Windows later was rewritten as a stand-alone operating system, borrowing so many features from another ( VAX VMS ) that

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