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Unreal Mode
In x86 computing, unreal mode, also big real mode, huge 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. Overview 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. HIMEM.SYS uses this feature to address extended memory, unless DOS is switched to run in a virtual 8086 mode t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computing
Computing is any goal-oriented activity requiring, benefiting from, or creating computing machinery. It includes the study and experimentation of algorithmic processes, and development of both 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 calculating. In earlier times, it was used in reference to the action performed by mechanical computing machines, and before that, to 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. Computing is intimately tied to the representation of numbers, though mathematical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
LILO (boot Loader)
LILO (Linux Loader) is a boot loader for Linux and was the default boot loader for most Linux distributions in the years after the popularity of loadlin. Today, many distributions use GRUB as the default boot loader, but LILO and its variant ELILO are still in wide use. Further development of LILO was discontinued in December 2015 along with a request by Joachim Wiedorn for potential developers. ELILO For EFI-based PC hardware the now orphaned ELILO boot loader was developed, originally by Hewlett-Packard for IA-64 systems made, but later also for standard i386 and amd64 hardware with EFI support. On any version of Linux running on Intel-based Apple Macintosh hardware, ELILO is one of the available bootloaders. It supports network booting using TFTP/DHCP. See also * /boot/ In Linux, and other Unix-like operating systems, the directory holds files used in booting the operating system. The usage is standardized in the Filesystem Hierarchy Standard. Contents The cont ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Prentice Hall International (UK) Limited
Prentice Hall was an American major educational publisher owned by Savvas Learning Company. Prentice Hall publishes print and digital content for the 6–12 and higher-education market, and distributes its technical titles through the Safari Books Online e-reference service. 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. Prentice Hall became known as a publisher of trade books by authors such as Norman Vincent Peale; elementary, secondary, and college textbooks; loose-leaf information services; and professional books. Prentice Hall acquired the training provider Deltak in 1979. Prentice Hall was acquired by Gulf+Western in 1984, and became part of that company's publishing division Simon & Schuster. S&S sold several Prentice Hall subsidiaries: Deltak and Resource Systems were sold to National Education ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
M&T Publishing, Inc
M&T may refer to: * Energy monitoring and targeting, an energy efficiency technique * Markt+Technik, a book publisher * M&T Bank M&T Bank Corporation (Manufacturers and Traders Trust Company) is an American bank holding company headquartered in Buffalo, New York. It operates 1680 branches in New York, New Jersey, Connecticut, Pennsylvania, Maine, Maryland, Massachusetts ..., an American bank holding company * Mortise and tenon, a woodworking technique {{dab ... [...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 o ... [...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 internationa ... [...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) = 232), 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 registers of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
X86 Assembly Language
x86 assembly language is the name for the family of assembly languages which provide some level of backward compatibility with CPUs back to the Intel 8008 microprocessor, which was launched in April 1972. It is used to produce object code for the x86 class of processors. Regarded as a programming language, assembly is ''machine-specific'' and '' low-level''. Like all assembly languages, x86 assembly uses mnemonics to represent fundamental CPU instructions, or machine code. Assembly languages are most often used for detailed and time-critical applications such as small real-time embedded systems, operating-system kernels, and device drivers, but can also be used for other applications, such as the game '' Roller Coaster Tycoon'', 99% of which was written in x86 assembly. A compiler will sometimes produce assembly code as an intermediate step when translating a high-level program into machine code. Keywords Mnemonics and opcodes Each x86 assembly instruction is represent ... [...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 TSRs to be "loaded high", preserving conventional memory. The technique probably first appeared with the development of CEMM, included with Compaq MS-DOS 3.31 in 1987. Microsoft's version first appeared, built-in, with Windows/386 2.1 in 1988 and as standalone EMM386.SYS with MS-DOS 4.01 in 1989; the more flexible EMM386.EXE version appeared in MS-DOS 5.0 in 1991. Just as the other expanded memory managers, 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 used by the MMU a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
LOADALL
LOADALL is the common name for two different, undocumented machine instructions of Intel 80286 and Intel 80386 processors, which allow access to areas of the internal processor state that are normally outside of the IA-32 API scope, like ''descriptor cache registers''. The LOADALL for 286 processors is encoded 0Fh 05h, while the LOADALL for 386 processors is 0Fh 07h. Both variants – as the name implies – load all CPU internal registers in one operation. LOADALL had the unique ability to set up the visible part of the segment registers (selector) independently of their corresponding cached part, allowing the programmer to bring the CPU into states not otherwise allowed by the official programming model. Usage As an example of the usefulness of these techniques, LOADALL can set up the CPU to allow access to all memory from real mode, without having to switch it into unreal mode (which requires switching into protected mode, accessing memory and finally switching back to re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Local Descriptor Table
The Global Descriptor Table (GDT) is a data structure used by Intel x86-family processors starting with the 80286 in order to define the characteristics of the various memory areas used during program execution, including the base address, the size, and access privileges like executability and writability. These memory areas are called x86 memory segmentation, segments in Intel terminology. Global Descriptor Table The GDT can hold things other than segment descriptors as well. Every 8-byte entry in the GDT is a descriptor, but these descriptors can be references not only to memory segments but also to Task State Segment (TSS), Local Descriptor Table (LDT), or Call Gate structures in memory. The last ones, Call Gates, are particularly important for transferring control between x86 privilege levels although this mechanism is not used on most modern operating systems. There is also a #Local Descriptor Table, Local Descriptor Table (LDT). Multiple LDTs can be defined in the GDT, but on ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Global Descriptor Table
The Global Descriptor Table (GDT) is a data structure used by Intel x86-family processors starting with the 80286 in order to define the characteristics of the various memory areas used during program execution, including the base address, the size, and access privileges like executability and writability. These memory areas are called segments in Intel terminology. Global Descriptor Table The GDT can hold things other than segment descriptors as well. Every 8-byte entry in the GDT is a descriptor, but these descriptors can be references not only to memory segments but also to Task State Segment (TSS), Local Descriptor Table (LDT), or Call Gate structures in memory. The last ones, Call Gates, are particularly important for transferring control between x86 privilege levels although this mechanism is not used on most modern operating systems. There is also a Local Descriptor Table (LDT). Multiple LDTs can be defined in the GDT, but only one is current at any one time: usually as ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
