A hardware bug is a bug in

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 ...

. It is the hardware counterpart of

software bug A software bug is a design defect ( bug) in computer software. A computer program with many or serious bugs may be described as ''buggy''. The effects of a software bug range from minor (such as a misspelled word in the user interface) to sev ...

, a defect in

software Software consists of computer programs that instruct the Execution (computing), execution of a computer. Software also includes design documents and specifications. The history of software is closely tied to the development of digital comput ...

. A bug is different from a

glitch A glitch is a short-lived technical fault, such as a transient one that corrects itself, making it difficult to troubleshoot. The term is particularly common in the computing and electronics industries, in circuit bending, as well as among pl ...

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 An erratum or corrigendum (: errata, corrigenda) (comes from ) is a correction of a published text. Generally, publishers issue an erratum for a production error (i.e., an error introduced during the publishing process) and a corrigendum for an a ...

, 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 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 ...

and

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 desi ...

of the

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 ...

computers are sometimes utilized.

Security vulnerabilities

Some flaws in hardware may lead to security vulnerabilities where memory protection or other features fail to work properly. Starting in 2017 a series of security vulnerabilities were found in the implementations of speculative execution on common processor architectures that allowed a violation of privilege level. In 2019 researchers discovered that a manufacturer debugging mode, known as VISA, had an undocumented feature on

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 compo ...

Platform Controller Hubs, known as chipsets, which made the mode accessible with a normal motherboard possibly leading to a security vulnerability.

Pentium bugs

The Intel

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 proce ...

series of CPUs had two well-known bugs discovered after it was brought to market, the FDIV bug affecting floating point division which resulted in a recall in 1994, and the F00F bug discovered in 1997 which causes the processor to stop operating until rebooted.

References

{{reflist Hardware bugs Engineering concepts