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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 terminate-and-stay-resident programs (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 conventio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extended Memory
In DOS memory management, extended memory refers to memory above the first megabyte (220 bytes) of address space in an IBM PC or compatible with an 80286 or later processor. The term is mainly used under the DOS and Windows operating systems. DOS programs, running in real mode or virtual x86 mode, cannot directly access this memory, but are able to do so through an application programming interface (API) called the ''Extended Memory Specification'' (XMS). This API is implemented by a driver (such as HIMEM.SYS) or the operating system kernel, which takes care of memory management and copying memory between conventional and extended memory, by temporarily switching the processor into protected mode. In this context, the term "extended memory" may refer to either the whole of the extended memory or only the portion available through this API. Extended memory can also be accessed directly by DOS programs running in protected mode using VCPI or DPMI, two (different and incompat ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Windows 9x
Windows 9x is a generic term referring to a line of discontinued Microsoft Windows operating systems released from 1995 to 2000 and supported until 2006, which were based on the kernel introduced in Windows 95 and modified in succeeding versions, with its underlying foundation based on MS-DOS. The first version in the 9x series was Windows 95, which was succeeded by Windows 98 and then Windows Me, which was the third and last version of Windows on the 9x line, until the series was superseded by Windows XP. Windows 9x is predominantly known for its use in home desktops. In 1998, Windows made up 82% of operating system market share. The internal release number for versions of Windows 9x is 4.x. The internal versions for Windows 95, 98, and Me are 4.0, 4.1, and 4.9, respectively. Previous MS-DOS-based versions of Windows used version numbers of 3.2 or lower. Windows NT, which was aimed at professional users such as networks and businesses, used a similar but separate version num ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
DR DOS "Panther"
DR-DOS is a disk operating system for IBM PC compatibles, originally developed by Gary A. Kildall's Digital Research, Digital Research, Inc. and derived from Concurrent PC DOS 6.0, which was an advanced successor of CP/M-86. Upon its introduction in 1988, it was the first DOS that attempted to be Binary compatibility, compatible with IBM PC DOS and MS-DOS. Its first release was version 3.31, named so that it would match MS-DOS's then-current version. DR DOS 5.0 was released in 1990 as the first to be sold in retail; it was critically acclaimed and led to DR DOS becoming the main rival to Microsoft's MS-DOS, who quickly responded with its own MS-DOS 5.0 but releasing over a year later. It introduced a graphical user interface layer called ViewMAX. DR DOS 6.0 was released in 1991; then with Novell's acquisition of Digital Research, the following version was named Novell DOS 7.0 in 1994. After another sale, to Caldera (company), Caldera, updated versions were released partly op ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extended Memory Specification
In DOS memory management, extended memory refers to memory above the first megabyte (220 bytes) of address space in an IBM PC or compatible with an 80286 or later processor. The term is mainly used under the DOS and Windows operating systems. DOS programs, running in real mode or virtual x86 mode, cannot directly access this memory, but are able to do so through an application programming interface (API) called the '' Extended Memory Specification'' (XMS). This API is implemented by a driver (such as HIMEM.SYS) or the operating system kernel, which takes care of memory management and copying memory between conventional and extended memory, by temporarily switching the processor into protected mode. In this context, the term "extended memory" may refer to either the whole of the extended memory or only the portion available through this API. Extended memory can also be accessed directly by DOS programs running in protected mode using VCPI or DPMI, two (different and i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intel 80386
The Intel 386, originally released as the 80386 and later renamed i386, is the third-generation x86 architecture microprocessor from Intel. It was the first 32-bit computing, 32-bit processor in the line, making it a significant evolution in the x86 architecture. Pre-production samples of the 386 were released to select developers in 1985, while mass production commenced in 1986. The 386 was the central processing unit, central processing unit (CPU) of many workstations and high-end personal computers of the time. The 386 began to fall out of public use starting with the release of the i486 processor in 1989, while in embedded systems the 386 remained in widespread use until Intel finally discontinued it in 2007. Compared to its predecessor the Intel 80286 ("286"), the 80386 added a three-stage instruction pipelining, instruction pipeline which it brings up to total of 6-stage instruction pipeline, extended the architecture from 16-bits to 32-bits, and added an on-chip memory ... [...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. It had a data size of 16 bits, and had an address width of 24 bits, which could address up to 16M of memory with a suitable operating system such as Windows compared to 1M for the 8086. The 80286 used approximately 134,000 transistors in its original nMOS ( HMOS) incarnation and, just like the contemporary 80186, it can 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Upper Memory Block
In DOS memory management, the upper memory area (UMA) is the memory between the addresses of 640 KB and 1024 KB ( 0xA0000–0xFFFFF) in an IBM PC or compatible. IBM reserved the uppermost 384 KB of the 8088 CPU's 1024 KB address space for BIOS ROM, Video BIOS, Option ROMs, video RAM, RAM on peripherals, memory-mapped I/O, and obsoleted ROM BASIC. However, even with video RAM, the ROM BIOS, the Video BIOS, the Option ROMs, and I/O ports for peripherals, much of this 384 KB of address space was unused. As the 640 KB memory restriction became ever more of an obstacle, techniques were found to fill the empty areas with RAM. These areas were referred to as upper memory blocks (UMBs). Usage The next stage in the evolution of DOS was for the operating system to use upper memory blocks (UMBs) and the high memory area (HMA). This occurred with the release of DR DOS 5.0 in 1990. DR DOS' built-in memory manager, EMM386.EXE, could per ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
SoftICE
SoftICE is a kernel mode debugger for DOS and Windows up to Windows XP. It is designed to run underneath Windows, so that the operating system is unaware of its presence. Unlike an application debugger, SoftICE is capable of suspending all operations in Windows when instructed. Due to its low-level capabilities, SoftICE is also popular as a software cracking tool. Microsoft offers two kernel-mode debuggers, WinDbg and KD, without charges. However, the full capabilities of WinDbg and KD are available only when two interlinked computers are used. SoftICE, therefore, is an exceptionally useful tool for difficult driver-related development. The last released version was for Windows XP. Older versions exist for DOS and compatible operating systems. SoftICE was originally produced by the company NuMega, and was subsequently acquired by Compuware in 1997, which in turn sold the property to Micro Focus in 2009. Currently, Micro Focus owns the source code and patents, but is not act ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NuMega
NuMega Technologies, Inc. (also known as NuMega), was a software company founded in 1987 by Frank Grossman and Jim Moskun in Nashua, New Hampshire. The company developed a Kernel mode debugger, now SoftICE, for DOS and the Windows NT family.Mark Russinovich o#64Podnutz (2:00/1:03:09)/ref> In 1995, the company acquired the Marquis Computing, Inc. assets VB/CodeReview and VB/FailSafe, and hired its president, Hank Marquis to manage NuMega Visual Basic products. In December 1997, the company was acquired by Compuware, when it became NuMega Labs of Compuware. Less than a year after moving to Merrimack, New Hampshire, Merrimack, the development lab was effectively shut down on 11 June 2007. In June 2009, Compuware sold the former NuMega products, the intellectual property and transferred the remaining staff to a UK-based firm named Micro Focus. Mark Russinovich, a software developer who now serves as CTO of Microsoft Azure, started his career at NuMega. Hank Marquis, who served as a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ring 0 (computer Security)
In computer science, hierarchical protection domains, often called protection rings, are mechanisms to protect data and functionality from faults (by improving fault tolerance) and malicious behavior (by providing computer security). Computer operating systems provide different levels of access to resources. A protection ring is one of two or more hierarchical ''levels'' or ''layers'' of privilege within the architecture of a computer system. This is generally hardware-enforced by some CPU architectures that provide different CPU modes at the hardware or microcode level. Rings are arranged in a hierarchy from most privileged (most trusted, usually numbered zero) to least privileged (least trusted, usually with the highest ring number). On most operating systems, Ring 0 is the level with the most privileges and interacts most directly with the physical hardware such as certain CPU functionality (e.g. the control registers) and I/O controllers. Special mechanisms are provided ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
EMM386
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 entr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
