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Hardware Bug
A hardware bug is a bug in computer hardware. It is the hardware counterpart of software bug, a defect in software. A bug is different from a glitch which describes an undesirable behavior as more quick, transient and repeated than constant, and different from a ''quirk'' which is a behavior that may be considered useful even though not intentionally designed. Errata, corrections to the documentation, may be published by the manufacturer to describe hardware bugs, and ''errata'' is sometimes used as a term for the bugs themselves. History Unintended operation Sometimes users take advantage of the unintended or undocumented operation of hardware to serve some purpose, in which case a flaw may be considered a feature. This gives rise to the often ironically employed acronym INABIAF, "It's Not A Bug It's A Feature". For example, undocumented instructions, known as illegal opcodes, on the MOS Technology 6510 of the Commodore 64 and MOS Technology 6502 of the Apple II computers ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bug (engineering)
In engineering, a bug is a design defect in an engineered system that causes an undesired result. Although used exclusively to describe a technical issue, ''bug'' is a non-technical term; applicable without technical understanding of the system. The term ''bug'' applies exclusively to a system that is (human) designed; not to a natural system; and that the issue is within the influence of human control. For example, humans have faults but not bugs, and a server crash due to natural disaster is not a bug. In addition to or instead of ''defect'', some use: error, flaw or fault. Engineered systems is a broad classification encompassing but not limited to: software, computer hardware, electronics, circuitry and machinery. The undesirable result can be classified and described ''many'' ways including: intermittent, transient, glitch, crash or hang. Since desirability is subjective, what is considered undesirable to one may be considered desirable to another; even a useful feat ... [...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] |
Pentium F00F Bug
The Pentium F00F bug is a design flaw in the majority of Intel Pentium, Pentium MMX, and Pentium OverDrive processors (all in the P5 microarchitecture). Discovered in 1997, it can result in the processor ceasing to function until the computer is physically rebooted. The bug has been circumvented through operating system updates. The name is shorthand for F0 0F C7 C8, the hexadecimal encoding of one offending instruction. More formally, the bug is called the ''invalid operand with locked CMPXCHG8B instruction bug''. Description In the x86 architecture, the byte sequence F0 0F C7 C8 represents the instruction lock cmpxchg8b eax (locked compare and exchange of 8 bytes in register EAX). The bug also applies to opcodes ending in C9 through CF, which specify register operands other than EAX. The F0 0F C7 C8 instruction does not require any special privileges. This instruction encoding is invalid. The cmpxchg8b instruction compares the value in the EDX and EAX registers with an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pentium FDIV Bug
The Pentium FDIV bug is a hardware bug affecting the floating-point unit (FPU) of the early Intel Pentium processors. Because of the bug, the processor would return incorrect binary floating point results when dividing certain pairs of high-precision numbers. The bug was discovered in 1994 by Thomas R. Nicely, a professor of mathematics at Lynchburg College. Missing values in a lookup table used by the FPU's floating-point division algorithm led to calculations acquiring small errors. In certain circumstances the errors can occur frequently and lead to significant deviations. The severity of the FDIV bug is debated. Though rarely encountered by most users (''Byte'' magazine estimated that 1 in 9 billion floating point divides with random parameters would produce inaccurate results), both the flaw and Intel's initial handling of the matter were heavily criticized by the tech community. In December 1994, Intel recalled the defective processors in what was the first full r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pentium
Pentium is a series of x86 architecture-compatible microprocessors produced by Intel from 1993 to 2023. The Pentium (original), original Pentium was Intel's fifth generation processor, succeeding the i486; Pentium was Intel's flagship processor line for over a decade until the introduction of the Intel Core line in 2006. Pentium-branded processors released from 2009 onwards were considered entry-level products positioned above the low-end Intel Atom, Atom and Celeron series, but below the faster Core lineup and workstation/server Xeon series. The later Pentiums, which have little more than their name in common with earlier Pentiums, were based on both the architecture used in Atom and that of Core processors. In the case of Atom architectures, Pentiums were the highest performance implementations of the architecture. Pentium processors with Core architectures prior to 2017 were distinguished from the faster, higher-end i-series processors by lower clock rates and disabling ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Intel
Intel Corporation is an American multinational corporation and technology company headquartered in Santa Clara, California, and Delaware General Corporation Law, incorporated in Delaware. Intel designs, manufactures, and sells computer components such as central processing units (CPUs) and related products for business and consumer markets. It is one of the world's List of largest semiconductor chip manufacturers, largest semiconductor chip manufacturers by revenue, and ranked in the Fortune 500, ''Fortune'' 500 list of the List of largest companies in the United States by revenue, largest United States corporations by revenue for nearly a decade, from 2007 to 2016 Fiscal year, fiscal years, until it was removed from the ranking in 2018. In 2020, it was reinstated and ranked 45th, being the List of Fortune 500 computer software and information companies, 7th-largest technology company in the ranking. It was one of the first companies listed on Nasdaq. Intel supplies List of I ... [...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] |
Speculative Execution
Speculative execution is an optimization (computer science), optimization technique where a computer system performs some task that may not be needed. Work is done before it is known whether it is actually needed, so as to prevent a delay that would have to be incurred by doing the work after it is known that it is needed. If it turns out the work was not needed after all, most changes made by the work are reverted and the results are ignored. The objective is to provide more Concurrency (computer science), concurrency if extra Resource (computer science), resources are available. This approach is employed in a variety of areas, including branch predictor, branch prediction in instruction pipeline, pipelined CPU, processors, value prediction for exploiting value locality, prefetching Instruction prefetch, memory and File system, files, and optimistic concurrency control in Relational database management system, database systems. Speculative multithreading is a special case of specu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apple II
Apple II ("apple Roman numerals, two", stylized as Apple ][) is a series of microcomputers manufactured by Apple Computer, Inc. from 1977 to 1993. The Apple II (original), original Apple II model, which gave the series its name, was designed by Steve Wozniak and was first sold on June 10, 1977. Its success led to it being followed by the Apple II Plus, Apple IIe, Apple IIc, and Apple IIc Plus, with the 1983 IIe being the most popular. The name is trademarked with square brackets as Apple ][, then, beginning with the IIe, as Apple //. The Apple II was a major advancement over its predecessor, the Apple I, in terms of ease of use, features, and expandability. It became one of several recognizable and successful computers throughout the 1980s, although this was mainly limited to the US. It was aggressively marketed through volume discounts and manufacturing arrangements to educational institutions, which made it the first computer in widespread use in American secondary ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Hardware
Computer hardware includes the physical parts of a computer, such as the central processing unit (CPU), random-access memory (RAM), motherboard, computer data storage, graphics card, sound card, and computer case. It includes external devices such as a Computer monitor, monitor, Computer mouse, mouse, Computer keyboard, keyboard, and Computer speakers, speakers. By contrast, software is a set of written instructions that can be stored and run by hardware. Hardware derived its name from the fact it is ''Hardness, hard'' or rigid with respect to changes, whereas software is ''soft'' because it is easy to change. Hardware is typically directed by the software to execute any command or Instruction (computing), instruction. A combination of hardware and software forms a usable computing system, although Digital electronics, other systems exist with only hardware. History Early computing devices were more complicated than the ancient abacus date to the seventeenth century. French ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MOS Technology 6502
The MOS Technology 6502 (typically pronounced "sixty-five-oh-two" or "six-five-oh-two") William Mensch and the moderator both pronounce the 6502 microprocessor as ''"sixty-five-oh-two"''. is an 8-bit computing, 8-bit microprocessor that was designed by a small team led by Chuck Peddle for MOS Technology. The design team had formerly worked at Motorola on the Motorola 6800 project; the 6502 is essentially a simplified, less expensive and faster version of that design. When it was introduced in 1975, the 6502 was the least expensive microprocessor on the market by a considerable margin. It initially sold for less than one-sixth the cost of competing designs from larger companies, such as the 6800 or Intel 8080. Its introduction caused rapid decreases in pricing across the entire processor market. Along with the Zilog Z80, it sparked a series of projects that resulted in the home computer microcomputer revolution, revolution of the early 1980s. Home video game consoles and home com ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Commodore 64
The Commodore 64, also known as the C64, is an 8-bit computing, 8-bit home computer introduced in January 1982 by Commodore International (first shown at the Consumer Electronics Show, January 7–10, 1982, in Las Vegas). It has been listed in the Guinness World Records as the highest-selling single computer model of all time, with independent estimates placing the number sold between 12.5 and 17 million units. Volume production started in early 1982, marketing in August for . Preceded by the VIC-20 and Commodore PET, the C64 took its name from its of RAM. With support for multicolor sprite (computer graphics), sprites and a custom chip for waveform generation, the C64 could create superior visuals and audio compared to systems without such custom hardware. The C64 dominated the low-end computer market (except in the UK, France and Japan, lasting only about six months in Japan) for most of the later years of the 1980s. For a substantial period (1983–1986), the C64 had betwe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
