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QIO
QIO (Queue I/O) is a term used in several computer operating systems designed by the former Digital Equipment Corporation ( DEC) of Maynard, Massachusetts. I/O operations on these systems are initiated by issuing a QIO call to the kernel. There are two types of QIO - Queue I/O, and Queue I/O and Wait. For QIO without wait, the call returns immediately. If the request is successfully enqueued, the actual operation occurs asynchronously. On completion, status is returned in the QIO status doubleword. The QIO request may also specify that completion set an event flag or issue an Asynchronous System Trap ( AST). The call may also be issued as QIOW (Queue I/O and Wait for completion), allowing synchronous I/O. In this case, the wait-for-event-flag operation is combined so the call does not return until the I/O operation completes or fails. The following operating systems implement QIO(W): * RSX-15 * RSX-11 (including all of the variants) * RSTS/E (synchronous only, emulated by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Event Flag
{{notability, date=March 2019 An event flag is a process synchronization primitive in the OpenVMS operating system. It has two possible states, ''set'' or ''cleared''. The following basic primitive operations are provided: * Set event flag ($SETEF) * Clear event flag ($CLREF) * Wait for event flag ($WAITFR)--if the flag was clear, this would make the process wait until it was set. If the flag was already set, this would immediately return, leaving the flag set. Additional synchronization operations are: * $WFLOR--wait for any of the specified event flags to be set. * $WFLAND--wait for ''all'' the specified event flags to be set. Event flags can be either ''local'' (per-process) or ''common'' (accessible by more than one process). Each process has its own set of 64 local flags, numbered 0-63. It is also possible to ''associate'' the process with up to 2 sets of common event flags. These come in sets of 32 each, and the process can assign them numbers 64-95 or 96-127. They come int ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asynchronous System Trap
Asynchronous System Trap (AST) refers to a mechanism used in several computer operating systems designed by the former Digital Equipment Corporation (DEC) of Maynard, Massachusetts. Mechanism Various events within these systems can be optionally signalled back to the user processes via the AST mechanism. These ASTs act like subroutine calls but they are delivered asynchronously, that is, without any regard to the context of the main thread. Because of this, care must be taken: * to ensure that any code that is shared between the main thread and the AST must be designed to be reentrant, and * any data that is shared must be safe against corruption if modified at any time by the AST. Otherwise, the data must be guarded by blocking ASTs during critical sections. ASTs are most commonly encountered as a result of issuing QIO calls to the kernel. Completion of the I/O can be signalled by the issuance of an AST to the calling process/task. Certain runtime errors could also be signall ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RSX-11
RSX-11 is a discontinued family of multi-user real-time operating systems for PDP-11 computers created by Digital Equipment Corporation. In widespread use through the late 1970s and early 1980s, RSX-11 was influential in the development of later operating systems such as OpenVMS, VMS and Windows NT. As the original ''Real-Time System Executive'' name suggests, RSX was designed (and commonly used) for real time use, with process control a major use, thereof. It was also popular for program development and general computing. History Name and origins RSX-11 began as a port to the PDP-11 architecture of the earlier RSX-15 operating system for the PDP-15 minicomputer, first released in 1971. The main architect for RSX-15 (later renamed XVM/RSX) was Dennis “Dan” Brevik. Commenting on the ''RSX'' acronym, Brevik says: RSX-11D and IAS The porting effort first produced small paper tape based real-time executives (RSX-11A, RSX-11C) which later gained limited support for disks (RSX ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RSTS/E
RSTS () is a multi-user time-sharing operating system developed by Digital Equipment Corporation (DEC, now part of Hewlett-Packard) for the PDP-11 series of 16-bit minicomputers. The first version of RSTS (RSTS-11, Version 1) was implemented in 1970 by DEC software engineers that developed the TSS-8 time-sharing operating system for the PDP-8. The last version of RSTS (RSTS/E, Version 10.1) was released in September 1992. RSTS-11 and RSTS/E are usually referred to just as "RSTS" and this article will generally use the shorter form. RSTS-11 supports the BASIC programming language, an extended version called BASIC-PLUS, developed under contract by ''Evans Griffiths & Hart'' of Boston,. Starting with RSTS/E version 5B, DEC added support for additional programming languages by emulating the execution environment of the RT-11 and RSX-11 operating systems. Acronyms and abbreviations *BTSS (Basic Time Sharing System – never marketed) – The first name for RSTS. *CCL (Concise Comm ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
OpenVMS
OpenVMS, often referred to as just VMS, is a multi-user, multiprocessing and virtual memory-based operating system. It is designed to support time-sharing, batch processing, transaction processing and workstation applications. Customers using OpenVMS include banks and financial services, hospitals and healthcare, telecommunications operators, network information services, and industrial manufacturers. During the 1990s and 2000s, there were approximately half a million VMS systems in operation worldwide. It was first announced by Digital Equipment Corporation (DEC) as VAX/VMS (''Virtual Address eXtension/Virtual Memory System'') alongside the VAX-11/780 minicomputer in 1977. OpenVMS has subsequently been ported to run on DEC Alpha systems, the Itanium-based HPE Integrity Servers, and select x86-64 hardware and hypervisors. Since 2014, OpenVMS is developed and supported by VMS Software Inc. (VSI). OpenVMS offers high availability through computer cluster, clustering — the ability ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asynchronous System Trap
Asynchronous System Trap (AST) refers to a mechanism used in several computer operating systems designed by the former Digital Equipment Corporation (DEC) of Maynard, Massachusetts. Mechanism Various events within these systems can be optionally signalled back to the user processes via the AST mechanism. These ASTs act like subroutine calls but they are delivered asynchronously, that is, without any regard to the context of the main thread. Because of this, care must be taken: * to ensure that any code that is shared between the main thread and the AST must be designed to be reentrant, and * any data that is shared must be safe against corruption if modified at any time by the AST. Otherwise, the data must be guarded by blocking ASTs during critical sections. ASTs are most commonly encountered as a result of issuing QIO calls to the kernel. Completion of the I/O can be signalled by the issuance of an AST to the calling process/task. Certain runtime errors could also be signall ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Operating System
An operating system (OS) is system software that manages computer hardware, software resources, and provides common services for computer programs. Time-sharing operating systems schedule tasks for efficient use of the system and may also include accounting software for cost allocation of processor time, mass storage, printing, and other resources. For hardware functions such as input and output and memory allocation, the operating system acts as an intermediary between programs and the computer hardware, although the application code is usually executed directly by the hardware and frequently makes system calls to an OS function or is interrupted by it. Operating systems are found on many devices that contain a computer from cellular phones and video game consoles to web servers and supercomputers. The dominant general-purpose personal computer operating system is Microsoft Windows with a market share of around 74.99%. macOS by Apple Inc. is in second place (14.84%), ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Digital Equipment Corporation
Digital Equipment Corporation (DEC ), using the trademark Digital, was a major American company in the computer industry from the 1960s to the 1990s. The company was co-founded by Ken Olsen and Harlan Anderson in 1957. Olsen was president until forced to resign in 1992, after the company had gone into precipitous decline. The company produced many different product lines over its history. It is best known for the work in the minicomputer market starting in the mid-1960s. The company produced a series of machines known as the PDP line, with the PDP-8 and PDP-11 being among the most successful minis in history. Their success was only surpassed by another DEC product, the late-1970s VAX "supermini" systems that were designed to replace the PDP-11. Although a number of competitors had successfully competed with Digital through the 1970s, the VAX cemented the company's place as a leading vendor in the computer space. As microcomputers improved in the late 1980s, especially w ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maynard, Massachusetts
Maynard is a town in Middlesex County, Massachusetts, United States. The town is located 22 miles west of Boston, in the MetroWest and Greater Boston region of Massachusetts and borders Acton, Concord, Stow and Sudbury. The town's population was 10,746 as of the 2020 United States Census. Maynard is located on the Assabet River, a tributary of the Concord River. A large part of the Assabet River National Wildlife Refuge is located within the town, and the Assabet River Rail Trail connects the Refuge and downtown Maynard to the South Acton commuter rail station. Historic downtown Maynard is home to many shops, restaurants, galleries, a movie theater, and the former Assabet Woolen Mill, which produced wool fabrics from 1846 to 1950, including cloth for Union Army uniforms during the Civil War. Maynard was the headquarters for Digital Equipment Corporation from 1957 to 1998. Owners of the former mill complex currently lease space to office and light-industry businesses. His ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kernel (computer Science)
The kernel is a computer program at the core of a computer's operating system and generally has complete control over everything in the system. It is the portion of the operating system code that is always resident in memory and facilitates interactions between hardware and software components. A full kernel controls all hardware resources (e.g. I/O, memory, cryptography) via device drivers, arbitrates conflicts between processes concerning such resources, and optimizes the utilization of common resources e.g. CPU & cache usage, file systems, and network sockets. On most systems, the kernel is one of the first programs loaded on startup (after the bootloader). It handles the rest of startup as well as memory, peripherals, and input/output (I/O) requests from software, translating them into data-processing instructions for the central processing unit. The critical code of the kernel is usually loaded into a separate area of memory, which is protected from access by applicatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RSX-15
The PDP-15 was the fifth and last of the 18-bit minicomputers produced by Digital Equipment Corporation. The PDP-1 was first delivered in December 1959 and the first PDP-15 was delivered in February 1970. More than 400 of these successors to the PDP-9 (and 9/L) were ordered within the first eight months. In addition to operating systems, the PDP-15 had compilers for Fortran and ALGOL. History The 18-bit PDP systems preceding the PDP-15 were named PDP-1, PDP-4, PDP-7 & PDP-9. The last PDP-15 was produced in 1979. Hardware The PDP-15 was DEC's only 18-bit machine constructed from TTL integrated circuits rather than discrete transistors, and, like every DEC 18-bit system could be equipped with: * an optional X-Y (point-plot or vector graphics) display. * a hardware floating point option, with a 10x speedup, was offered. * up to 128Kwords of core main memory Models The PDP-15 models offered by DEC were: * PDP-15/10: a 4K-word paper-tape based system * PDP-15/20: 8K, added DEC ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Run-time System
In computer programming, a runtime system or runtime environment is a sub-system that exists both in the computer where a program is created, as well as in the computers where the program is intended to be run. The name comes from the compile time and runtime division from compiled languages, which similarly distinguishes the computer processes involved in the creation of a program (compilation) and its execution in the target machine (the run time). Most programming languages have some form of runtime system that provides an environment in which programs run. This environment may address a number of issues including the management of application memory, how the program accesses variables, mechanisms for passing parameters between procedures, interfacing with the operating system, and otherwise. The compiler makes assumptions depending on the specific runtime system to generate correct code. Typically the runtime system will have some responsibility for setting up and managin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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