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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] |
FlexOS 286
FlexOS is a discontinued modular real-time multiuser multitasking operating system ( RTOS) designed for computer-integrated manufacturing, laboratory, retail and financial markets. Developed by Digital Research's Flexible Automation Business Unit in Monterey, California, in 1985, the system was considered to become a successor of Digital Research's earlier Concurrent DOS, but with a new, modular, and considerably different system architecture and portability across several processor families. Still named Concurrent DOS 68K and Concurrent DOS 286, it was renamed into FlexOS on 1 October 1986 to better differentiate the target audiences. FlexOS was licensed by several OEMs who selected it as the basis for their own operating systems like 4680 OS, 4690 OS, S5-DOS/MT and others. Unrelated to FlexOS, the original Concurrent DOS system architecture found a continuation in successors like Concurrent DOS XM and Concurrent DOS 386 as well. Overview Concurrent DOS 286, Concurrent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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] |
Concurrent DOS 286
Multiuser DOS is a real-time multi-user multi-tasking operating system for IBM PC-compatible microcomputers. An evolution of the older Concurrent CP/M-86, Concurrent DOS and Concurrent DOS 386 operating systems, it was originally developed by Digital Research and acquired and further developed by Novell in 1991. Its ancestry lies in the earlier Digital Research 8-bit operating systems CP/M and MP/M, and the 16-bit single-tasking CP/M-86 which evolved from CP/M. When Novell abandoned Multiuser DOS in 1992, the three master value-added resellers (VARs) DataPac Australasia, Concurrent Controls and Intelligent Micro Software were allowed to take over and continued independent development into Datapac Multiuser DOS and System Manager, CCI Multiuser DOS, and IMS Multiuser DOS and REAL/32. The FlexOS line, which evolved from Concurrent DOS 286 and Concurrent DOS 68K, was sold off to Integrated Systems, Inc. (ISI) in July 1994. Concurrent CP/M-86 The initial version of CP/ ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intel 80286
The Intel 80286 (also marketed as the iAPX 286 and often called Intel 286) is a 16-bit microprocessor that was introduced on February 1, 1982. It was the first 8086-based CPU with separate, non- multiplexed address and data buses and also the first with memory management and wide protection abilities. The 80286 used approximately 134,000 transistors in its original nMOS (HMOS) incarnation and, just like the contemporary 80186, it could correctly execute most software written for the earlier Intel 8086 and 8088 processors. The 80286 was employed for the IBM PC/AT, introduced in 1984, and then widely used in most PC/AT compatible computers until the early 1990s. In 1987, Intel shipped its five-millionth 80286 microprocessor. History and performance Intel's first 80286 chips were specified for a maximum clockrate of 5, 6 or 8 MHz and later releases for 12.5 MHz. AMD and Harris later produced 16 MHz, 20 MHz and 25 MHz parts, respectively. Intersil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Invalid Opcode Handler
An illegal opcode, also called an unimplemented operation, unintended opcode or undocumented instruction, is an instruction to a CPU that is not mentioned in any official documentation released by the CPU's designer or manufacturer, which nevertheless has an effect. Illegal opcodes were common on older CPUs designed during the 1970s, such as the MOS Technology 6502, Intel 8086, and the Zilog Z80. On these older processors, many exist as a side effect of the wiring of transistors in the CPU, and usually combine functions of the CPU that were not intended to be combined. On old and modern processors, there are also instructions intentionally included in the processor by the manufacturer, but that are not documented in any official specification. The effect of many illegal opcodes, on many processors, is just a trap to an error handler. However, some processors that trap for most illegal opcodes do not do so for some illegal opcodes, and some other processors do not check for i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
HIMEM
HIMEM.SYS is a DOS device driver which allows DOS programs to store data in extended memory according to the Extended Memory Specification (XMS). The memory beyond the first 1 MB of address space is required by Windows 9x/ Me in order to load; therefore, these versions of Microsoft Windows require HIMEM.SYS to be loaded to be able to run. HIMEM.SYS was first included with Windows 2.1 (1988). In MS-DOS 5.0 (1991) and later, HIMEM.SYS can be used to load the DOS kernel code into the High Memory Area (HMA) to increase the amount of available conventional memory by specifying DOS=HIGH in CONFIG.SYS. In DR DOS 5.0 (1990) and 6.0 (1991), the driver is named HIDOS.SYS rather than HIMEM.SYS, like the corresponding DCONFIG.SYS or CONFIG.SYS directive HIDOS=ON. In FreeDOS, the matching file is named HIMEM.EXE and can be loaded from the FreeDOS configuration file named FDCONFIG.SYS or CONFIG.SYS. In Windows 3.1 and Windows 9x, there is also a command-line loadable vers ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Undocumented Machine Instruction
An illegal opcode, also called an unimplemented operation, unintended opcode or undocumented instruction, is an instruction to a CPU that is not mentioned in any official documentation released by the CPU's designer or manufacturer, which nevertheless has an effect. Illegal opcodes were common on older CPUs designed during the 1970s, such as the MOS Technology 6502, Intel 8086, and the Zilog Z80. On these older processors, many exist as a side effect of the wiring of transistors in the CPU, and usually combine functions of the CPU that were not intended to be combined. On old and modern processors, there are also instructions intentionally included in the processor by the manufacturer, but that are not documented in any official specification. The effect of many illegal opcodes, on many processors, is just a trap to an error handler. However, some processors that trap for most illegal opcodes do not do so for some illegal opcodes, and some other processors do not check for i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Real Mode
Real mode, also called real address mode, is an operating mode of all x86-compatible CPUs. The mode gets its name from the fact that addresses in real mode always correspond to real locations in memory. Real mode is characterized by a 20-bit segmented memory address space (giving 1 MB of addressable memory) and unlimited direct software access to all addressable memory, I/O addresses and peripheral hardware. Real mode provides no support for memory protection, multitasking, or code privilege levels. Before the release of the 80286, which introduced protected mode, real mode was the only available mode for x86 CPUs; and for backward compatibility, all x86 CPUs start in real mode when reset, though it is possible to emulate real mode on other systems when starting on other modes. History The 286 architecture introduced protected mode, allowing for (among other things) hardware-level memory protection. Using these new features, however, required a new operating system that was ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Los Angeles Securities Group
LOS, or Los, or LoS may refer to: Science and technology * Length of stay, the duration of a single episode of hospitalisation * Level of service, a measure used by traffic engineers * Level of significance, a measure of statistical significance * Line-of-sight (other) * LineageOS, a free and open-source operating system for smartphones and tablet computers * Loss of signal ** Fading **End of pass (spaceflight) * Loss of significance, undesirable effect in calculations using floating-point arithmetic Medicine and biology * Lipooligosaccharide, a bacterial lipopolysaccharide with a low-molecular-weight * Lower oesophageal sphincter Arts and entertainment * ''The Land of Stories'', a series of children's novels by Chris Colfer * Los, or the Crimson King, a character in Stephen King's novels * Los (band), a British indie rock band from 2008 to 2011 * Los (Blake), a character in William Blake's poetry * Los (rapper) (born 1982), stage name of American rapper C ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intel 80386
The Intel 386, originally released as 80386 and later renamed i386, is a 32-bit microprocessor introduced in 1985. The first versions had 275,000 transistorsmit.edu—The Future of FPGAs (Cornell) October 11, 2012 and were the of many workstations and high-end s of the time. As the original implementation of the [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digital Research
Digital Research, Inc. (DR or DRI) was a company created by Gary Kildall to market and develop his CP/M operating system and related 8-bit, 16-bit and 32-bit systems like MP/M, Concurrent DOS, FlexOS, Multiuser DOS, DOS Plus, DR DOS and GEM. It was the first large software company in the microcomputer world. Digital Research was originally based in Pacific Grove, California, later in Monterey, California. Overview In 1972, Gary Kildall, an instructor at the Naval Postgraduate School in Monterey, California, began working at Intel as a consultant under the business name Microcomputer Applications Associates (MAA). By 1974, he had developed Control Program/Monitor, or CP/M, the first disk operating system for microcomputers. In 1974 he incorporated as Intergalactic Digital Research, with his wife handling the business side of the operation. The company soon began operating under its shortened name Digital Research. The company's operating systems, starting with CP ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Windows/386 2
Windows 2.0 is a major release of Microsoft Windows, a family of graphical operating systems for personal computers developed by Microsoft. It was released to manufacturing on December 9, 1987, as a successor to Windows 1.0. The product includes two different variants, a base edition for 8086 real mode, and Windows/386, an enhanced edition for i386 protected mode. Windows 2.0 differs from its predecessor by allowing users to overlap and resize application windows, while the operating environment also introduced desktop icons, keyboard shortcuts, and support for 16-color VGA graphics. It also introduced Microsoft Word and Excel, and integrated the Control Panel. Noted as an improvement of its predecessor, Microsoft Windows gained more sales and popularity after the release of the operating environment, although it is also considered to be the incarnation that remained a work in progress. Due to the introduction of overlapping windows, Apple Inc. had filed a lawsuit again ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
