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Zilog Z280
The Zilog Z280 is a 16-bit microprocessor designed by Zilog as an enhancement of the Zilog Z80 architecture and integrating improvements from the abandoned Zilog Z800 project. First introduced in July 1987, the Z280 is considered to be a commercial failure. The Z280 was fabricated in CMOS, added a memory management unit (MMU) to expand the addressing range to 16 MB, features for multitasking and multiprocessor and coprocessor configurations, and 256 bytes of on-chip static RAM, configurable as either a cache for instructions and/or data, or as part of the ordinary address space. It has a huge number of new instructions and addressing modes giving a total of over 2000 combinations. It offers Supervisor and User operating modes, and optionally separate address spaces for instructions and data in both modes (four total possible address spaces). Its crystal or external clock signal is divided by half to drive the CPU. The CPU clock can be further divided by 1, 2, or 4 tim ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Z280 PLCC 1987
Z, or z, is the twenty-sixth and last letter of the Latin alphabet. It is used in the modern English alphabet, in the alphabets of other Western European languages, and in others worldwide. Its usual names in English are ''zed'' (), which is most commonly used in British English, and ''zee'' (), most commonly used in American English, with an occasional archaic variant ''izzard'' ()."Z", ''Oxford English Dictionary,'' 2nd edition (1989); ''Merriam-Webster's Third New International Dictionary of the English Language, Unabridged'' (1993); "zee", ''op. cit''. Name In most English-speaking countries, including Australia, Canada, India, Ireland, New Zealand, South Africa and the United Kingdom, the letter's name is ''zed'' , reflecting its derivation from the Greek letter ''zeta'' (this dates to Latin, which borrowed Y and Z from Greek), but in American English its name is ''zee'' , analogous to the names for B, C, D, etc., and deriving from a late 17th-century English dialect ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Bus
In computer architecture, a bus (historically also called a data highway or databus) is a communication system that transfers data between components inside a computer or between computers. It encompasses both hardware (e.g., wires, optical fiber) and software, including communication protocols. At its core, a bus is a shared physical pathway, typically composed of wires, traces on a circuit board, or busbars, that allows multiple devices to communicate. To prevent conflicts and ensure orderly data exchange, buses rely on a communication protocol to manage which device can transmit data at a given time. Buses are categorized based on their role, such as system buses (also known as internal buses, internal data buses, or memory buses) connecting the CPU and memory. Expansion buses, also called peripheral buses, extend the system to connect additional devices, including peripherals. Examples of widely used buses include PCI Express (PCIe) for high-speed internal connectio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Multiprocessor
Multiprocessing (MP) is the use of two or more central processing units (CPUs) within a single computer system. The term also refers to the ability of a system to support more than one processor or the ability to allocate tasks between them. There are many variations on this basic theme, and the definition of multiprocessing can vary with context, mostly as a function of how CPUs are defined ( multiple cores on one die, multiple dies in one package, multiple packages in one system unit, etc.). A multiprocessor is a computer system having two or more processing units (multiple processors) each sharing main memory and peripherals, in order to simultaneously process programs. A 2009 textbook defined multiprocessor system similarly, but noted that the processors may share "some or all of the system’s memory and I/O facilities"; it also gave tightly coupled system as a synonymous term. At the operating system level, ''multiprocessing'' is sometimes used to refer to the executio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Burst Mode (computing)
Burst may refer to: *Burst mode (other), a mode of operation where events occur in rapid succession **Burst transmission Burst may refer to: *Burst mode (other), a mode of operation where events occur in rapid succession **Burst transmission, a term in telecommunications **Burst switching, a feature of some packet-switched networks **Bursting, a signaling mo ..., a term in telecommunications ** Burst switching, a feature of some packet-switched networks ** Bursting, a signaling mode of neurons * Burst phase, a feature of the PAL television format * Burst fracture, a type of spinal injury * Burst charge, a component of some fireworks * Burst noise, type of electronic noise that occurs in semiconductors *Burst (coin), a cryptocurrency *Burst finish, a two- or three-color faded effect applied to musical instruments e.g. sunburst (finish) * Burst (village), a village in Erpe-Mere * Burst.com, a software company * Burst Radio, the University of Bristol student radio st ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Coprocessor
A coprocessor is a computer processor used to supplement the functions of the primary processor (the CPU). Operations performed by the coprocessor may be floating-point arithmetic, graphics, signal processing, string processing, cryptography or I/O interfacing with peripheral devices. By offloading processor-intensive tasks from the main processor, coprocessors can accelerate system performance. Coprocessors allow a line of computers to be customized, so that customers who do not need the extra performance do not need to pay for it. Functionality Coprocessors vary in their degree of autonomy. Some (such as FPUs) rely on direct control via coprocessor instructions, embedded in the CPU's instruction stream. Others are independent processors in their own right, capable of working asynchronously; they are still not optimized for general-purpose code, or they are incapable of it due to a limited instruction set focused on accelerating specific tasks. It is common for these to b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Illegal Instruction
An illegal opcode, also called an unimplemented operation, unintended opcode or undocumented instruction, is an instruction to a CPU that is not mentioned in any official documentation released by the CPU's designer or manufacturer, which nevertheless has an effect. Illegal opcodes were common on older CPUs designed during the 1970s, such as the MOS Technology 6502, Intel 8086, and the Zilog Z80. Unlike modern processors, those older processors have a very limited transistor budget, and thus to save space their designers often omitted circuitry to detect invalid opcodes and generate a trap to an error handler. The operation of many of these opcodes happens as a side effect of the wiring of transistors in the CPU, and usually combines functions of the CPU that were not intended to be combined. On old and modern processors, there are also instructions intentionally included in the processor by the manufacturer, but that are not documented in any official specification. Overview ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Privilege (computing)
In computing, privilege is defined as the delegation of authority to perform security-relevant functions on a computer system. A privilege allows a user to perform an action with security consequences. Examples of various privileges include the ability to create a new user, install software, or change kernel functions. Users who have been delegated extra levels of control are called privileged. Users who lack most privileges are defined as unprivileged, regular, or normal users. Theory Privileges can either be automatic, granted, or applied for. An automatic privilege exists when there is no requirement to have permission to perform an action. For example, on systems where people are required to log into a system to use it, logging out will not require a privilege. Systems that do not implement file protection - such as MS-DOS - essentially give unlimited privilege to perform any action on a file. A granted privilege exists as a result of presenting some credential to the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Supervisor Mode
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] |
Trap (computing)
In digital computers, an interrupt (sometimes referred to as a trap) is a request for the processor to ''interrupt'' currently executing code (when permitted), so that the event can be processed in a timely manner. If the request is accepted, the processor will suspend its current activities, save its state, and execute a function called an ''interrupt handler'' (or an ''interrupt service routine'', ISR) to deal with the event. This interruption is often temporary, allowing the software to resume normal activities after the interrupt handler finishes, although the interrupt could instead indicate a fatal error. Interrupts are commonly used by hardware devices to indicate electronic or physical state changes that require time-sensitive attention. Interrupts are also commonly used to implement computer multitasking and system calls, especially in real-time computing. Systems that use interrupts in these ways are said to be interrupt-driven. History Hardware interrupts were ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Dynamic Memory Allocation
Memory management (also dynamic memory management, dynamic storage allocation, or dynamic memory allocation) is a form of resource management applied to computer memory. The essential requirement of memory management is to provide ways to dynamically allocate portions of memory to programs at their request, and free it for reuse when no longer needed. This is critical to any advanced computer system where more than a single process might be underway at any time. Several methods have been devised that increase the effectiveness of memory management. Virtual memory systems separate the memory addresses used by a process from actual physical addresses, allowing separation of processes and increasing the size of the virtual address space beyond the available amount of RAM using paging or swapping to secondary storage. The quality of the virtual memory manager can have an extensive effect on overall system performance. The system allows a computer to appear as if it may have more ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Memory Protection
Memory protection is a way to control memory access rights on a computer, and is a part of most modern instruction set architectures and operating systems. The main purpose of memory protection is to prevent a process from accessing memory that has not been allocated to it. This prevents a bug or malware within a process from affecting other processes, or the operating system itself. Protection may encompass all accesses to a specified area of memory, write accesses, or attempts to execute the contents of the area. An attempt to access unauthorized memory results in a hardware fault, e.g., a segmentation fault, storage violation exception, generally causing abnormal termination of the offending process. Memory protection for computer security includes additional techniques such as address space layout randomization and executable-space protection. Methods Segmentation Segmentation refers to dividing a computer's memory into segments. A reference to a memory locatio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Instruction Pipelining
In computer engineering, instruction pipelining is a technique for implementing instruction-level parallelism within a single processor. Pipelining attempts to keep every part of the processor busy with some instruction by dividing incoming instructions into a series of sequential steps (the eponymous "pipeline") performed by different processor units with different parts of instructions processed in parallel. Concept and motivation In a pipelined computer, instructions flow through the central processing unit (CPU) in stages. For example, it might have one stage for each step of the von Neumann cycle: Fetch the instruction, fetch the operands, do the instruction, write the results. A pipelined computer usually has "pipeline registers" after each stage. These store information from the instruction and calculations so that the logic gates of the next stage can do the next step. This arrangement lets the CPU complete an instruction on each clock cycle. It is common for even-nu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
