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Screen reader
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Screen reader
A screen reader is a form of assistive technology (AT) that renders text and image content as speech or braille output. Screen readers are essential to blind people, and are also useful to people who are visually impaired, illiterate or learning-disabled. Screen readers are software applications that attempt to convey what people with normal eyesight see on a display to their users via non-visual means, like text-to-speech, sound icons, or a braille device. They do this by applying a wide variety of techniques that include, for example, interacting with dedicated accessibility APIs, using various operating system features (like inter-process communication and querying user interface properties), and employing hooking techniques.
Microsoft Windows operating systems have included the Microsoft Narrator screen reader since Windows 2000, though separate products such as Freedom Scientific's commercially available JAWS screen reader and ZoomText screen magnifier and the free and open source screen reader NVDA by NV Access are more popular for that operating system. Apple Inc.'s macOS, iOS, and tvOS include VoiceOver as a built-in screen reader, while Google's Android provides the Talkback screen reader and its ChromeOS can use ChromeVox. Similarly, Android-based devices from Amazon provide the VoiceView screen reader. There are also free and open source screen readers for Linux and Unix-like systems, such as Speakup and Orca.
Around 1978, Al Overby of IBM Raleigh developed a prototype of a talking terminal, known as SAID (for Synthetic Audio Interface Driver), for the IBM 3270 terminal. SAID read the ASCII values of the display in a stream and spoke them through a large vocal track synthesizer the size of a suitcase, and it cost around $10,000. Dr. Jesse Wright, a blind research mathematician, and Jim Thatcher, formerly his graduate student from the University of Michigan, working as mathematicians for IBM, adapted this as an internal IBM tool for use by blind people. After the early IBM Personal Computer (PC) was released in 1981, Thatcher and Wright developed a software equivalent to SAID, called PC-SAID, or Personal Computer Synthetic Audio Interface Driver. This was renamed and released in 1984 as IBM Screen Reader, which became the proprietary eponym for that general class of assistive technology.
In early operating systems, such as MS-DOS, which employed command-line interfaces (CLIs), the screen display consisted of characters mapping directly to a screen buffer in memory and a cursor position. Input was by keyboard. All this information could therefore be obtained from the system either by hooking the flow of information around the system and reading the screen buffer or by using a standard hardware output socket and communicating the results to the user.
In the 1980s, the Research Centre for the Education of the Visually Handicapped (RCEVH) at the University of Birmingham developed a Screen Reader for the BBC Micro and NEC Portable.
With the arrival of graphical user interfaces (GUIs), the situation became more complicated. A GUI has characters and graphics drawn on the screen at particular positions, and therefore there is no purely textual representation of the graphical contents of the display. Screen readers were therefore forced to employ new low-level techniques, gathering messages from the operating system and using these to build up an "off-screen model", a representation of the display in which the required text content is stored.
For example, the operating system might send messages to draw a command button and its caption. These messages are intercepted and used to construct the off-screen model. The user can switch between controls (such as buttons) available on the screen and the captions and control contents will be read aloud and/or shown on a refreshable braille display.
Screen readers can also communicate information on menus, controls, and other visual constructs to permit blind users to interact with these constructs. However, maintaining an off-screen model is a significant technical challenge; hooking the low-level messages and maintaining an accurate model are both difficult tasks.[citation needed]
Hub AI
Screen reader AI simulator
(@Screen reader_simulator)
Screen reader
A screen reader is a form of assistive technology (AT) that renders text and image content as speech or braille output. Screen readers are essential to blind people, and are also useful to people who are visually impaired, illiterate or learning-disabled. Screen readers are software applications that attempt to convey what people with normal eyesight see on a display to their users via non-visual means, like text-to-speech, sound icons, or a braille device. They do this by applying a wide variety of techniques that include, for example, interacting with dedicated accessibility APIs, using various operating system features (like inter-process communication and querying user interface properties), and employing hooking techniques.
Microsoft Windows operating systems have included the Microsoft Narrator screen reader since Windows 2000, though separate products such as Freedom Scientific's commercially available JAWS screen reader and ZoomText screen magnifier and the free and open source screen reader NVDA by NV Access are more popular for that operating system. Apple Inc.'s macOS, iOS, and tvOS include VoiceOver as a built-in screen reader, while Google's Android provides the Talkback screen reader and its ChromeOS can use ChromeVox. Similarly, Android-based devices from Amazon provide the VoiceView screen reader. There are also free and open source screen readers for Linux and Unix-like systems, such as Speakup and Orca.
Around 1978, Al Overby of IBM Raleigh developed a prototype of a talking terminal, known as SAID (for Synthetic Audio Interface Driver), for the IBM 3270 terminal. SAID read the ASCII values of the display in a stream and spoke them through a large vocal track synthesizer the size of a suitcase, and it cost around $10,000. Dr. Jesse Wright, a blind research mathematician, and Jim Thatcher, formerly his graduate student from the University of Michigan, working as mathematicians for IBM, adapted this as an internal IBM tool for use by blind people. After the early IBM Personal Computer (PC) was released in 1981, Thatcher and Wright developed a software equivalent to SAID, called PC-SAID, or Personal Computer Synthetic Audio Interface Driver. This was renamed and released in 1984 as IBM Screen Reader, which became the proprietary eponym for that general class of assistive technology.
In early operating systems, such as MS-DOS, which employed command-line interfaces (CLIs), the screen display consisted of characters mapping directly to a screen buffer in memory and a cursor position. Input was by keyboard. All this information could therefore be obtained from the system either by hooking the flow of information around the system and reading the screen buffer or by using a standard hardware output socket and communicating the results to the user.
In the 1980s, the Research Centre for the Education of the Visually Handicapped (RCEVH) at the University of Birmingham developed a Screen Reader for the BBC Micro and NEC Portable.
With the arrival of graphical user interfaces (GUIs), the situation became more complicated. A GUI has characters and graphics drawn on the screen at particular positions, and therefore there is no purely textual representation of the graphical contents of the display. Screen readers were therefore forced to employ new low-level techniques, gathering messages from the operating system and using these to build up an "off-screen model", a representation of the display in which the required text content is stored.
For example, the operating system might send messages to draw a command button and its caption. These messages are intercepted and used to construct the off-screen model. The user can switch between controls (such as buttons) available on the screen and the captions and control contents will be read aloud and/or shown on a refreshable braille display.
Screen readers can also communicate information on menus, controls, and other visual constructs to permit blind users to interact with these constructs. However, maintaining an off-screen model is a significant technical challenge; hooking the low-level messages and maintaining an accurate model are both difficult tasks.[citation needed]
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