|
VAX-11 780
The VAX-11 is a discontinued family of 32-bit superminicomputers, running the Virtual Address eXtension (VAX) instruction set architecture (ISA), developed and manufactured by Digital Equipment Corporation (DEC). Development began in 1976. In addition to being powerful machines in their own right, they also offer the additional ability to run user mode PDP-11 code (thus the -11 in VAX-11), offering an upward compatible path for existing customers. The first machine in the series, the VAX-11/780, was announced in October 1977. Its former competitors in the minicomputer space, like Data General and Hewlett-Packard, were unable to successfully respond to the introduction and rapid update of the VAX design. DEC followed the VAX-11/780 with the lower-cost 11/750, and the even lower cost 11/730 and 11/725 models in 1982. More powerful models, initially known as the VAX-11/790 and VAX-11/795, were instead rebranded as the VAX 8600 series. The VAX-11 line was discontinued in 1988, havin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
VAX 11-780 Intero
VAX (an acronym for Virtual Address eXtension) is a series of computers featuring a 32-bit instruction set architecture (ISA) and virtual memory that was developed and sold by Digital Equipment Corporation (DEC) in the late 20th century. The VAX-11/780, introduced October 25, 1977, was the first of a range of popular and influential computers implementing the VAX ISA. The VAX family was a huge success for DEC – over 100 models were introduced over the lifetime of the design, with the last members arriving in the early 1990s. The VAX was succeeded by the DEC Alpha, which included several features from VAX machines to make porting from the VAX easier. VAX was designed as a successor to the 16-bit PDP-11, one of the most successful minicomputers in history with approximately 600,000 examples sold. The system was designed to offer backward compatibility with the PDP-11 while extending the memory to a full 32-bit implementation and adding demand paged virtual memory. The name VAX ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Schottky Transistor
A Schottky transistor is a combination of a transistor and a Schottky diode that prevents the transistor from saturating by diverting the excessive input current. It is also called a Schottky-clamped transistor. Mechanism Standard transistor-transistor logic (TTL) uses transistors as saturated switches. A saturated transistor is turned on hard, which means it has a lot more base drive than it needs for the collector current it is drawing. The extra base drive creates a stored charge in the base of the transistor. The stored charge causes problems when the transistor needs to be switched from on to off: while the charge is present, the transistor is on; all the charge must be removed before the transistor will turn off. Removing the charge takes time (called storage time), so the result of saturation is a delay between the applied turn-off input at the base and the voltage swing at the collector. Storage time accounts for a significant portion of the propagation delay in the o ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Gate Array
A gate array is an approach to the design and manufacture of application-specific integrated circuits (ASICs) using a prefabricated chip with components that are later interconnected into logic devices (e.g. NAND gates, flip-flops, etc.) according to a custom order by adding metal interconnect layers in the factory. It was popular during upheaval in semiconductor industry in 80s and its usage declined by end of 90s. Similar technologies have also been employed to design and manufacture analog, analog-digital, and structured arrays, but, in general, these are not called gate arrays. Gate arrays have also been known as ''uncommitted logic arrays'' (''ULAs''), which also offered linear circuit functions, and ''semi-custom chips''. History Development Gate arrays had several concurrent development paths. Ferranti in the UK pioneered commercializing bipolar ULA technology, offering circuits of "100 to 10,000 gates and above" by 1983. The company's early lead in semi-custom chips, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bipolar Junction Transistor
A bipolar junction transistor (BJT) is a type of transistor that uses both electrons and electron holes as charge carriers. In contrast, a unipolar transistor, such as a field-effect transistor, uses only one kind of charge carrier. A bipolar transistor allows a small current injected at one of its terminals to control a much larger current flowing between the terminals, making the device capable of amplification or switching. BJTs use two p–n junctions between two semiconductor types, n-type and p-type, which are regions in a single crystal of material. The junctions can be made in several different ways, such as changing the doping of the semiconductor material as it is grown, by depositing metal pellets to form alloy junctions, or by such methods as diffusion of n-type and p-type doping substances into the crystal. The superior predictability and performance of junction transistors quickly displaced the original point-contact transistor. Diffused transistors, along wi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Logic Family
In computer engineering, a logic family is one of two related concepts: * A logic family of monolithic digital integrated circuit devices is a group of electronic logic gates constructed using one of several different designs, usually with compatible logic levels and power supply characteristics within a family. Many logic families were produced as individual components, each containing one or a few related basic logical functions, which could be used as "building-blocks" to create systems or as so-called "glue" to interconnect more complex integrated circuits. * A logic family may also be a set of techniques used to implement logic within VLSI integrated circuits such as central processors, memories, or other complex functions. Some such logic families use static techniques to minimize design complexity. Other such logic families, such as domino logic, use clocked dynamic techniques to minimize size, power consumption and delay. Before the widespread use of integrated circuits, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Asymmetric Multiprocessing
An asymmetric multiprocessing (AMP or ASMP) system is a multiprocessor computer system where not all of the multiple interconnected central processing units (CPUs) are treated equally. For example, a system might allow (either at the hardware or operating system level) only one CPU to execute operating system code or might allow only one CPU to perform I/O operations. Other AMP systems might allow any CPU to execute operating system code and perform I/O operations, so that they were symmetric with regard to processor roles, but attached some or all peripherals to particular CPUs, so that they were asymmetric with respect to the peripheral attachment. Asymmetric multiprocessing was the only method for handling multiple CPUs before symmetric multiprocessing (SMP) was available. It has also been used to provide less expensive options on systems where SMP was available. Background and history For the room-size computers of the 1960s and 1970s, a cost-effective way to increase compute ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
VAX Unit Of Performance
The VAX Unit of Performance, or VUP for short, is an obsolete measurement of computer performance used by Digital Equipment Corporation (DEC). 1 VUP was equivalent to the performance of a VAX 11/780 completing a given task. Other VAX machines and later workstation designs were compared in performance terms by defining system speed in VUPs, for instance, the VAXft Model 310 ran at 3.8 VUPs, meaning it ran roughly 3.8 times as fast as the 11/780. The term was used largely within the DEC and its community, and fell from use as more standard ratings like SPEC became more widely used. This was especially true with the introduction of DEC workstations running Unix Unix (; trademarked as UNIX) is a family of multitasking, multiuser computer operating systems that derive from the original AT&T Unix, whose development started in 1969 at the Bell Labs research center by Ken Thompson, Dennis Ritchie, and ot ..., in which case the VUP was of little use comparing the platforms to comp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
VMScluster
A VMScluster, originally known as a VAXcluster, is a computer cluster involving a group of computers running the OpenVMS operating system. Whereas tightly coupled multiprocessor systems run a single copy of the operating system, a VMScluster is loosely coupled: each machine runs its own copy of OpenVMS, but the disk storage, lock manager, and security domain are all cluster-wide, providing a single system image abstraction. Machines can join or leave a VMScluster without affecting the rest of the cluster. For enhanced availability, VMSclusters support the use of dual-ported disks connected to two machines or storage controllers simultaneously. Initial release Digital Equipment Corporation (DEC) first announced VAXclusters in May 1983. At this stage, clustering required specialised communications hardware, as well as some major changes to low-level subsystems in VMS. The software and hardware were designed jointly. VAXcluster support was first added in VAX/VMS V4.0, which was rele ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Massbus
The Massbus is a high-performance computer input/output bus designed in the 1970s by Digital Equipment Corporation (DEC). The architecture development was sponsored by Gordon Bell and John Levy was the principal architect. The bus was used by Digital to interconnect its highest-performance computers with magnetic disk and magnetic tape storage equipment. The use of a common bus was intended to allow a single controller design to handle multiple peripheral models, and allowed the PDP-10, PDP-11, and VAX computer families to share a common set of peripherals. At the time there were multiple operating systems for each of the 16-bit, 32-bit, and 36-bit computer lines. The 18-bit PDP-15/40 connected to Massbus peripherals via a PDP-11 front end. An engineering goal was to reduce the need for a new driver per peripheral per operating system per computer family. Also, a major technical goal was to place any magnetic technology changes (data separators) into the storage device rather th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unibus
The Unibus was the earliest of several computer bus and backplane designs used with PDP-11 and early VAX systems manufactured by the Digital Equipment Corporation (DEC) of Maynard, Massachusetts. The Unibus was developed around 1969 by Gordon Bell and student Harold McFarland while at Carnegie Mellon University. The name refers to the unified nature of the bus; Unibus was used both as a system bus allowing the central processing unit to communicate with main memory, as well as a peripheral bus, allowing peripherals to send and receive data. Unifying these formerly separate busses allowed external devices to easily perform direct memory access (DMA) and made the construction of device drivers easier as control and data exchange was all handled through memory-mapped I/O. Unibus was physically large, which led to the introduction of Q-bus, which multiplexed some signals to reduce pin count. Higher performance PDP systems used Fastbus, essentially two Unibusses in one. The syst ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Error Correcting Code
In computing, telecommunication, information theory, and coding theory, an error correction code, sometimes error correcting code, (ECC) is used for controlling errors in data over unreliable or noisy communication channels. The central idea is the sender encodes the message with redundant information in the form of an ECC. The redundancy allows the receiver to detect a limited number of errors that may occur anywhere in the message, and often to correct these errors without retransmission. The American mathematician Richard Hamming pioneered this field in the 1940s and invented the first error-correcting code in 1950: the Hamming (7,4) code. ECC contrasts with error detection in that errors that are encountered can be corrected, not simply detected. The advantage is that a system using ECC does not require a reverse channel to request retransmission of data when an error occurs. The downside is that there is a fixed overhead that is added to the message, thereby requiring a h ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
_Cross-section.svg "Click for more on -> Bipolar Junction Transistor")
