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Unreal Mode
In x86 computing, unreal mode, also big real mode, flat real mode, or voodoo mode is a variant of real mode, in which one or more segment descriptors has been loaded with non-standard values, like 32-bit limits allowing access to the entire memory. Contrary to its name, it is not a separate addressing mode that the x86 processors can operate in. It is used in the 80286 and later x86 processors. Mechanism For efficiency reasons, the 80286 and all later x86 processors use the base address, size and other attributes stored in their internal segment descriptor cache whenever computing effective memory addresses, even in real mode. Therefore, a modification of the internal segment descriptor allows altering some properties of segments in real mode, like the size of addressable memory. This technique became widely used and is supported by all Intel processors. A program in unreal mode can call 16-bit code programmed for real mode (BIOS, DOS kernel and drivers) without any thunking ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computing
Computing is any goal-oriented activity requiring, benefiting from, or creating computer, computing machinery. It includes the study and experimentation of algorithmic processes, and the development of both computer hardware, hardware and software. Computing has scientific, engineering, mathematical, technological, and social aspects. Major computing disciplines include computer engineering, computer science, cybersecurity, data science, information systems, information technology, and software engineering. The term ''computing'' is also synonymous with counting and calculation, calculating. In earlier times, it was used in reference to the action performed by Mechanical computer, mechanical computing machines, and before that, to Computer (occupation), human computers. History The history of computing is longer than the history of computing hardware and includes the history of methods intended for pen and paper (or for chalk and slate) with or without the aid of tables. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Global Descriptor Table
The Global Descriptor Table (GDT) is a core part of Intel's x86 architecture that helps manage how memory is accessed and protected. Introduced with the Intel 80286 processor, it plays a key role in defining memory segments and their attributes: the base address, the size, and access privileges like executability and writability. Even though modern 64-bit systems rarely rely on segmentation, the GDT remains a required component for starting up the processor and managing certain system-level tasks. Description The GDT helps isolate memory between application software and the operating system. In protected mode (a more advanced processor mode that allows memory protection), the GDT defines: * Code segments: regions of memory that contain executable instructions. * Data segments: areas used to store program data. * System segments, like the Task State Segment (TSS), which is used for multitasking support. Each entry in the GDT is 8 or 16 bytes long and holds a segment descr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Addison Wesley Publishing Company
Addison–Wesley is an American publisher of textbooks and computer literature. It is an imprint of Pearson plc, a global publishing and education company. In addition to publishing books, Addison–Wesley also distributes its technical titles through the O'Reilly Online Learning e-reference service. Addison–Wesley's majority of sales derive from the United States (55%) and Europe (22%). The Addison–Wesley Professional Imprint produces content including books, eBooks, and video for the professional IT worker including developers, programmers, managers, system administrators. Classic titles include ''The Art of Computer Programming'', '' The C++ Programming Language'', ''The Mythical Man-Month'', and ''Design Patterns''. History Lew Addison Cummings and Melbourne Wesley Cummings founded Addison–Wesley in 1942, with the first book published by Addison–Wesley being Massachusetts Institute of Technology professor Francis Weston Sears' ''Mechanics''. Its first computer ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prentice Hall International (UK) Limited
Prentice Hall was a major American educational publisher. It published print and digital content for the 6–12 and higher-education market. It was an independent company throughout the bulk of the twentieth century. In its last few years it was owned by, then absorbed into, Savvas Learning Company. In the Web era, it distributed its technical titles through the Safari Books Online e-reference service for some years. History On October 13, 1913, law professor Charles Gerstenberg and his student Richard Ettinger founded Prentice Hall. Gerstenberg and Ettinger took their mothers' maiden names, Prentice and Hall, to name their new company. At the time the name was usually styled as Prentice-Hall (as seen for example on many title pages), per an orthographic norm for coordinate elements within such compounds (compare also ''McGraw-Hill'' with later styling as ''McGraw Hill''). Prentice-Hall became known as a publisher of trade books by authors such as Norman Vincent Peale; eleme ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
M&T Publishing, Inc , a woodworking technique
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M&T may refer to: * Energy monitoring and targeting, an energy efficiency technique * Markt+Technik, a book publisher * M&T Bank, an American bank holding company * Mortise and tenon A mortise and tenon (occasionally mortice and tenon) is a Woodworking joints, joint that connects two pieces of wood or other material. Woodworking, Woodworkers around the world have used it for thousands of years to join pieces of wood, mainly ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
People's Computer Company
People's Computer Company (PCC) was an organization, a newsletter (the ''People's Computer Company Newsletter'') and, later, a quasiperiodical called the ''Dragonsmoke''. PCC was founded and produced by Dennis Allison, Bob Albrecht and George Firedrake in Menlo Park, California in the early 1970s. The first newsletter, published in October 1972, announced itself with the following introduction: Computers are mostly used against people instead of for people; used to control people instead of to free them; Time to change all that - we need a... Peoples Computer Company. It was published bimonthly. The name was chosen in reference to Janis Joplin's rock group Big Brother and the Holding Company. The newsletter ceased publication in 1981. History PCC was one of the first organizations to recognize the potential of Tiny BASIC in the nascent field of personal computing when it published that language's design specification in their newsletter. This ultimately led to the design of a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Springer Science & Business Media
Springer Science+Business Media, commonly known as Springer, is a German multinational publishing company of books, e-books and peer-reviewed journals in science, humanities, technical and medical (STM) publishing. Originally founded in 1842 in Berlin, it expanded internationally in the 1960s, and through mergers in the 1990s and a sale to venture capitalists it fused with Wolters Kluwer and eventually became part of Springer Nature in 2015. Springer has major offices in Berlin, Heidelberg, Dordrecht, and New York City. History Julius Springer founded Springer-Verlag in Berlin in 1842 and his son Ferdinand Springer grew it from a small firm of 4 employees into Germany's then second-largest academic publisher with 65 staff in 1872.Chronology ". Springer Science+Business Media. In 1964, Springer expanded its business internationally, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
A20 Line
The A20, or address line 20, is one of the electrical lines that make up the system bus of an x86-based computer system. The A20 line in particular is used to transmit the 21st bit on the address bus. A microprocessor typically has a number of address lines equal to the base-two logarithm of the number of words in its physical address space. For example, a processor with 4 GB of byte-addressable physical space requires 32 lines (log2(4 GB) = log2(232 B) = 32), which are named A0 through A31. The lines are named after the zero-based number of the bit in the address that they are transmitting. The least significant bit is first and is therefore numbered bit 0 and signaled on line A0. A20 transmits bit 20 (the 21st bit) and becomes active once addresses reach 1 MB, or 220. Overview The Intel 8086, Intel 8088, and Intel 80186 processors had 20 address lines, numbered A0 to A19; with these, the processor can access 220 bytes, or 1 MB. Internal address re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
X86 Assembly Language
x86 assembly language is a family of Low-level programming language, low-level programming languages that are used to produce object code for the x86 class of processors. These languages provide backward compatibility with CPUs dating back to the Intel 8008 microprocessor, introduced in April 1972. As assembly languages, they are closely tied to the architecture's machine code instructions, allowing for precise control over hardware. In x86 assembly languages, mnemonics are used to represent fundamental CPU instructions, making the code more human-readable compared to raw machine code. Each mnemonics corresponds to a basic operation performed by the processor, such as arithmetic calculations, data movement, or Control flow, control flow decisions. Assembly languages are most commonly used in applications where performance and efficiency are critical. This includes Real-time operating system, real-time embedded systems, operating system, operating-system Kernel (operating system) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Global EMM Import Specification
EMM386 is the expanded memory manager of Microsoft's MS-DOS, IBM's PC DOS, Digital Research's DR-DOS, and Datalight's ROM-DOS which is used to create expanded memory using extended memory on Intel 80386 CPUs. There also is an EMM386.EXE available in FreeDOS. Overview EMM386.EXE can map memory into unused blocks in the upper memory area (UMA), allowing device drivers and terminate-and-stay-resident programs to be "loaded high", preserving conventional memory. The technique probably first appeared with the development of CEMM, included with Compaq's OEM MS-DOS for the Compaq Deskpro 386 in 1986. Microsoft's version first appeared, built-in, with Windows/386 2.0 in 1987 and as standalone EMM386.SYS with MS-DOS 4.0 in 1988; the more flexible EMM386.EXE version appeared in MS-DOS 5.0 in 1991. EMM386 uses the processor's virtual 8086 mode. This forces memory accesses made by DOS applications to go through the processor's MMU (introduced in the 386), and the page table entries ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DOSBox
DOSBox is a free and open-source MS-DOS emulator. It supports running programs primarily video games that are otherwise inaccessible since hardware for running a compatible disk operating system (DOS) is obsolete and generally unavailable today. It was first released in 2002, when DOS technology was becoming obsolete. Its adoption for running DOS games is relatively widespread; partially driven by its use in commercial re-releases of games. Development Before Windows XP, consumer-oriented versions of Windows were based on MS-DOS. Windows 3.0 and its updates were operating environments that ran on top of MS-DOS, and the Windows 9x series consisted of operating systems that were still based on MS-DOS. These versions of Windows could run DOS applications. Conversely, the Windows NT operating systems were not based on DOS. A member of the series, Windows XP, debuted on October 25, 2001, and became the first consumer-oriented version of Windows to not use DOS. Althou ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bochs
Bochs (pronounced "box") is a portable IA-32 and x86-64 IBM PC compatible emulator and debugger mostly written in C++ and distributed as free software under the GNU Lesser General Public License. It supports emulation of the processor(s) (including protected mode), memory, disks, display, Ethernet, BIOS and common hardware peripherals of PCs. Many guest operating systems can be run using the emulator including DOS, several versions of Linux, Xenix, Microsoft Windows, BSDs and Rhapsody OS ( precursor of Mac OS X Public Beta). Bochs runs on many host operating systems, including Android OS, Linux, macOS, PlayStation 2, Windows, and Windows CE along with its derivatives. Bochs is mostly used for operating system development (when an emulated operating system crashes, it does not crash the host operating system, so the emulated OS can be debugged) and to run other guest operating systems inside already running host operating systems. It can also be used to run older software ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
