|
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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
|
 |
IBM PC Memory Areas
International Business Machines Corporation (using the trademark IBM), nicknamed Big Blue, is an American Multinational corporation, multinational technology company headquartered in Armonk, New York, and present in over 175 countries. It is a publicly traded company and one of the 30 companies in the Dow Jones Industrial Average. IBM is the largest industrial research organization in the world, with 19 research facilities across a dozen countries; for 29 consecutive years, from 1993 to 2021, it held the record for most annual U.S. patents generated by a business. IBM was founded in 1911 as the Computing-Tabulating-Recording Company (CTR), a holding company of manufacturers of record-keeping and measuring systems. It was renamed "International Business Machines" in 1924 and soon became the leading manufacturer of Tabulating machine, punch-card tabulating systems. During the 1960s and 1970s, the IBM mainframe, exemplified by the IBM System/360, System/360 and its successors, wa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
 |
Expansion Card
In computing, an expansion card (also called an expansion board, adapter card, peripheral card or accessory card) is a printed circuit board that can be inserted into an electrical connector, or expansion slot (also referred to as a bus slot) on a computer's motherboard (see also backplane) to add functionality to a computer system. Sometimes the design of the computer's case and motherboard involves placing most (or all) of these slots onto a separate, removable card. Typically such cards are referred to as a riser card in part because they project upward from the board and allow expansion cards to be placed above and parallel to the motherboard. Expansion cards allow the capabilities and interfaces of a computer system to be extended or supplemented in a way appropriate to the tasks it will perform. For example, a high-speed multi-channel data acquisition system would be of no use in a personal computer used for bookkeeping, but might be a key part of a system used for in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
 |
Keyboard Controller (computing)
In computing, a keyboard controller is a device that interfaces a keyboard (computing), keyboard to a computer. Its main function is to inform the computer when a computer keyboard keys, key is pressed or released. When data from the keyboard arrives, the controller raises an interrupt (a ''keyboard interrupt'') to allow the CPU to handle the input. If a keyboard is a separate computer peripheral, peripheral system unit (such as in most modern desktop computers), the keyboard controller is not directly attached to the keys, but receives scancodes from a microcontroller embedded in the keyboard via some kind of serial interface. In this case, the controller usually also controls the keyboard's LEDs by sending data back to keyboard through the wire. The IBM PC AT used an Intel 8042 chip to interface to the keyboard. This chip had two additional functions: it controlled access to the Intel 80286 CPU's A20 line in order to implement a workaround for a chip bug, and it was used to in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
|
X86 Memory Segmentation
x86 memory segmentation is a term for the kind of memory segmentation characteristic of the Intel x86 computer instruction set architecture. The x86 architecture has supported memory segmentation since the original Intel 8086 (1978), but ''x86 memory segmentation'' is a plainly descriptive retronym. The introduction of memory segmentation mechanisms in this architecture reflects the legacy of earlier 80xx processors, which initially could only address 16, or later 64 KB of memory (16,384 or 65,536 bytes), and whose instructions and registers were optimised for the latter. Dealing with larger addresses and more memory was thus comparably slower, as that capability was somewhat grafted-on in the Intel 8086. Memory segmentation could keep programs compatible, relocatable in memory, and by confining significant parts of a program's operation to 64 KB segments, the program could still run faster. In 1982, the Intel 80286 added support for virtual memory and memory pr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
|
 |
IBM PC/AT
The IBM Personal Computer AT (model 5170, abbreviated as IBM AT or PC/AT) was released in 1984 as the fourth model in the IBM Personal Computer line, following the IBM PC/XT and its IBM Portable PC variant. It was designed around the Intel 80286 microprocessor. Name IBM did not specify an expanded form of ''AT'' on the machine, press releases, brochures or documentation, but some sources expand the term as ''Advanced Technology'', including at least one internal IBM document. History IBM's 1984 introduction of the AT was seen as an unusual move for the company, which typically waited for competitors to release new products before producing its own models. At $4,000–6,000, it was only slightly more expensive than considerably slower IBM models. The announcement surprised rival executives, who admitted that matching IBM's prices would be difficult. No major competitor showed a comparable computer at COMDEX Las Vegas that year. Features The AT is IBM PC compatible, with t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
|
Terminate-and-stay-resident Program
A terminate-and-stay-resident program (commonly TSR) is a computer program running under DOS that uses a system call to return control to DOS as though it has finished, but remains in computer memory so it can be reactivated later. This technique partially overcame DOS's limitation of executing only one program, or task, at a time. TSRs are used only in DOS, not in Windows. Some TSRs are utility software that a computer user might call up several times a day, while working in another program, by using a hotkey. Borland Sidekick was an early and popular example of this type. Others serve as device drivers for hardware that the operating system does not directly support. Use Normally DOS can run only one program at a time. When a program finishes, it returns control to DOS using the system call of the DOS API. The memory and system resources used are then marked as unused. This makes it impossible to restart parts of the program without having to reload it all. Howev ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
|
 |
IBM PC/XT
The IBM Personal Computer XT (model 5160, often shortened to PC/XT) is the second computer in the IBM Personal Computer line, released on March 8, 1983. Except for the addition of a built-in hard drive and extra expansion slots, it is very similar to the original IBM PC model 5150 from 1981. Name IBM did not specify an expanded form of "XT" on the machine, press releases, brochures or documentation, but some publications expanded the term as "''eXtended Technology''" or just "''eXTended''". Features The XT was regarded as an incremental improvement over the PC and a disappointment compared to the next-generation successor that some had anticipated. Compared to the original IBM PC, the XT has the following major differences: * The number of expansion slots was increased from five to eight * Base RAM was increased to at least 128 KB * 2x32KB ROM ICs replace the previous 5x8KB ROM ICs * A 10 MB hard drive was included on most sub-models, with a disk controller featu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |
|
Device Driver
In the context of an operating system, a device driver is a computer program that operates or controls a particular type of device that is attached to a computer or automaton. A driver provides a software interface to hardware devices, enabling operating systems and other computer programs to access hardware functions without needing to know precise details about the hardware being used. A driver communicates with the device through the computer bus or communications subsystem to which the hardware connects. When a calling program invokes a routine in the driver, the driver issues commands to the device (drives it). Once the device sends data back to the driver, the driver may invoke routines in the original calling program. Drivers are hardware dependent and operating-system-specific. They usually provide the interrupt handling required for any necessary asynchronous time-dependent hardware interface. Purpose The main purpose of device drivers is to provide abstraction b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] [Amazon] |