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VCPI
In computing, the Virtual Control Program Interface (VCPI) is a specification published in 1989 by Phar Lap Software that allows a DOS program to run in protected mode, granting access to many features of the processor not available in real mode. It was supplanted by DOS Protected Mode Interface (DPMI) shortly after being introduced, due in large part to VCPI's inability to work in Windows 3.0's protected mode. Overview Developed since 1987 in cooperation with Quarterdeck Office Systems and with support by A.I. Architects, Lotus Development Corp., Quadram, Qualitas and Rational Systems, VCPI is provided by an expanded memory manager in DOS (e.g. CEMM, QEMM, later EMM386) and does allow 80386 protected-mode DOS extenders to coexist with 80386 EMS expanded memory emulators. It was eclipsed by DPMI, most notably because it was not supported for DOS programs run in Windows 3.0's native protected mode (called ''386 enhanced mode'') and because VCPI runs programs in Ring 0, which ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DOS Protected Mode Interface
In computing, the DOS Protected Mode Interface (DPMI) is a specification introduced in 1989 which allows a DOS program to run in protected mode, giving access to many features of the new PC processors of the time not available in real mode. It was initially developed by Microsoft for Windows 3.0, although Microsoft later turned control of the specification over to an industry committee with open membership. Almost all modern DOS extenders are based on DPMI and allow DOS programs to address all memory available in the PC and to run in protected mode (mostly in ring (computer security), ring 3, least privileged). Overview DPMI stands for DOS Protected Mode Interface. It is an API that allows a program to run in protected mode on 80286 series and later processors, and do the calls to real mode without having to set up these CPU modes manually. DPMI also provides the functions for managing various resources, notably Computer Memory, memory. This allows the DPMI-enabled programs to ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
QEMM
Quarterdeck Expanded Memory Manager (QEMM) is a memory manager produced by Quarterdeck Office Systems in the late 1980s through the late 1990s. It was the most popular third-party memory manager for the MS-DOS and other DOS operating systems. QEMM product ranges ;QRAM: A memory manager for Intel 80286 or higher CPUs. It supports Chips and Technologies chipsets. 2.02 added SHADOWRAM switch. QEXT correctly reallocates eXtended Memory Specification (XMS). It includes VIDRAM, Optimize, LOADHI from QEMM 6.02, Manifest 1.13. Earlier versions of QRAM also supported the older 8086 and 8088 CPUs. ;QEMM Game Edition: It is a version of QEMM that includes Quarterdeck GameRunner. Patches for regular QEMM do not work on QEMM Game Edition. ;QEMM MegaBundle: In the version shipped with Borland SideKick for Windows, it is a version with SideBar 1.00 (1994-08-22) and QEMM 7.5. ;DESQview 386: It includes DESQview and QEMM-386. Features/tools QEMM driver QEMM provides access to the Upper Mem ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DOS Protected Mode Services
DOS Protected Mode Services (DPMS) is a set of extended DOS memory management services to allow DPMS-enabled DOS drivers to load and execute in extended memory and protected mode. Not being a DOS extender by itself, DPMS is a minimal set of extended DOS memory management services to allow slightly modified DOS resident system extensions ( RSX) such as device drivers or TSRs (as so called ''DPMS clients'') to relocate themselves into extended memory and run in 16-bit or 32-bit protected mode while leaving only a tiny stub in conventional memory as an interface to communicate with the conventional DOS environment. The DPMS clients do so through DPMS services provided by a previously loaded ''DPMS server''. The necessary size of the remaining stub depends on the type of driver, but often can be reduced to a few hundred bytes for just the header even for complex drivers. By executing the driver in extended memory and freeing up conventional memory, DPMS not only allows very lar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phar Lap (company)
Phar Lap Software, Inc., was a software company specializing in software development tools for DOS operating systems. The company was named after the champion New Zealand racehorse Phar Lap. They were most noted for their software allowing developers to access memory beyond the 640 KiB limit of DOS (DOS extenders) and were an author of the VCPI standard. Phar Lap Software, Inc. was founded in April 1986 by Richard M. Smith, Robert Moote, and John M. Benfatto. Their first major success, ''386, DOS-Extender'', a 32-bit protected mode development tool, was released in November 1986. Phar Lap’s product line was expanded to include ''386, VMM'', a virtual memory add-in driver, ''LinkLoc'', a linker-locator for embedded development; cross tools for embedded development; and ''286, DOS-Extender'', a DOS extender that emulated an OS/2 environment, complete with the OS/2 API and protected mode, in contrast with Microsoft's OS/2 API emulation, which ran OS/2 applications in real mode a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
OS/2
OS/2 (Operating System/2) is a series of computer operating systems, initially created by Microsoft and IBM under the leadership of IBM software designer Ed Iacobucci. As a result of a feud between the two companies over how to position OS/2 relative to Microsoft's new Windows 3.1 operating environment, the two companies severed the relationship in 1992 and OS/2 development fell to IBM exclusively. The name stands for "Operating System/2", because it was introduced as part of the same generation change release as IBM's " Personal System/2 (PS/2)" line of second-generation personal computers. The first version of OS/2 was released in December 1987 and newer versions were released until December 2001. OS/2 was intended as a protected-mode successor of PC DOS. Notably, basic system calls were modeled after MS-DOS calls; their names even started with "Dos" and it was possible to create "Family Mode" applications – text mode applications that could work on both systems. Be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DOS Memory Management
In IBM PC compatible computing, DOS memory management refers to software and techniques employed to give applications access to more than 640 kibibytes (640*1024 bytes) (KiB) of "conventional memory". The 640 KiB limit was specific to the IBM PC and close compatibles; other machines running MS-DOS had different limits, for example the Apricot PC could have up to 768 KiB and the Sirius Victor 9000, 896 KiB. Memory management on the IBM family was made complex by the need to maintain backward compatibility to the original PC design and real-mode DOS, while allowing computer users to take advantage of large amounts of low-cost memory and new generations of processors. Since DOS has given way to Microsoft Windows and other 32-bit operating systems not restricted by the original arbitrary 640 KiB limit of the IBM PC, managing the memory of a personal computer no longer requires the user to manually manipulate internal settings and parameters of the system. The 640 KiB limit imposed g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
CEMM
CEMM, for Compaq Expanded Memory Manager was the first so-called PC " memory manager" for Intel 80386 CPUs, able to provide expanded memory (EMS) emulation by using the virtual memory features and the virtual 8086 mode of the CPU. It was present in Compaq DOS 3.10, shipping with the Compaq Deskpro 386 in September 1986. Overview In 1986, Compaq was the first vendor to ship a PC compatible computer with a 386 CPU, the Deskpro 386, and it was natural for them to develop solutions leveraging the specific features of their new hardware and in this case allowing existing EMS-compatible DOS programs to access all the memory. The implementation was not without its drawbacks. Although CEMM was called an "expanded memory manager", it was really a tiny, protected mode, single tasking operating system kernel, also called a virtual machine monitor (VMM). It had to catch all the interrupts and all the exceptions, and to ''reflect'' them to the virtual machine where DOS ran. This slowed the mac ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Multiuser DOS Federation
The Multiuser DOS Federation (MDOS) was an industry alliance to promote the growth and acceptance of multi-user DOS-based solutions on Intel 80286, 286, Intel 80386, 386 and Intel 80486, 486 computers. It was formed in July 1990. Initially among them were Digital Research, Theos Software, SunRiver, DigiBoard, Alloy Computer Products, Alloy, Viewport International and others. The idea was to reduce costs by allowing workgroups to run DOS applications from a shared Personal Computer, PC while working on terminals or workstations. On 18 February 1991, several members of the Multiuser DOS Federation issued a press release regarding their intentions to support DOS Protected Mode Interface, DPMI (mostly DPMI 1.0) in their products including Alloy Computer Products Inc. (PC-PLUS), Bluebird Systems, Inc. (Bluebird SuperDOS, SuperDOS), Concurrent Controls, Inc. (CCI Concurrent DOS 386, CCI Multiuser DOS), Digital Research, Inc. (DR Multiuser DOS), S&H Computer Systems, Inc. (TSX-32), StarPa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Expanded Memory
In DOS memory management, expanded memory is a system of bank switching that provided additional memory to DOS programs beyond the limit of conventional memory (640 KiB). ''Expanded memory'' is an umbrella term for several incompatible technology variants. The most widely used variant was the Expanded Memory Specification (EMS), which was developed jointly by Lotus Software, Intel, and Microsoft, so that this specification was sometimes referred to as "LIM EMS". LIM EMS had several versions. The first widely implemented version was EMS 3.2, which supported up to 8 MiB of expanded memory and uses parts of the address space normally dedicated to communication with peripherals (upper memory) to map portions of the expanded memory. EEMS, an expanded-memory management standard competing with LIM EMS 3.x, was developed by AST Research, Quadram and Ashton-Tate ("AQA"); it could map any area of the lower 1 MiB. EEMS ultimately was incorporated in LIM EMS 4.0, which supporte ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protected Mode
In computing, protected mode, also called protected virtual address mode, is an operational mode of x86-compatible central processing units (CPUs). It allows system software to use features such as virtual memory, paging and safe multi-tasking designed to increase an operating system's control over application software. When a processor that supports x86 protected mode is powered on, it begins executing instructions in real mode, in order to maintain backward compatibility with earlier x86 processors. Protected mode may only be entered after the system software sets up one descriptor table and enables the Protection Enable (PE) bit in the control register 0 (CR0). Protected mode was first added to the x86 architecture in 1982, with the release of Intel's 80286 (286) processor, and later extended with the release of the 80386 (386) in 1985. Due to the enhancements added by protected mode, it has become widely adopted and has become the foundation for all subsequent enhancements ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intel
Intel Corporation is an American multinational corporation and technology company headquartered in Santa Clara, California. It is the world's largest semiconductor chip manufacturer by revenue, and is one of the developers of the x86 series of instruction sets, the instruction sets found in most personal computers (PCs). Incorporated in Delaware, Intel ranked No. 45 in the 2020 ''Fortune'' 500 list of the largest United States corporations by total revenue for nearly a decade, from 2007 to 2016 fiscal years. Intel supplies microprocessors for computer system manufacturers such as Acer, Lenovo, HP, and Dell. Intel also manufactures motherboard chipsets, network interface controllers and integrated circuits, flash memory, graphics chips, embedded processors and other devices related to communications and computing. Intel (''int''egrated and ''el''ectronics) was founded on July 18, 1968, by semiconductor pioneers Gordon Moore (of Moore's law) and Robert Noyce ( ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Microsoft Corporation
Microsoft Corporation is an American multinational corporation, multinational technology company, technology corporation producing Software, computer software, consumer electronics, personal computers, and related services headquartered at the Microsoft Redmond campus located in Redmond, Washington, United States. Its best-known software products are the Microsoft Windows, Windows line of operating systems, the Microsoft Office Productivity software#Office suite, suite, and the Internet Explorer and Microsoft Edge, Edge web browsers. Its flagship hardware products are the Xbox video game consoles and the Microsoft Surface lineup of touchscreen personal computers. Microsoft ranked No. 21 in the 2020 Fortune 500 rankings of the largest United States corporations by total revenue; it was the world's List of the largest software companies, largest software maker by revenue as of 2019. It is one of the Big Tech, Big Five American information technology companies, alongside Alphabet ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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