overclocking
<hardware>
Any adjustments made to computer hardware, or less commonly software, to make its CPU run at a higher clock rate than intended by the original manufacturers. Typically this involves replacing the crystal in the clock generation circuitry with a higher frequency one or changing jumper settings or software configuration.
If the clock rate is increased too far, eventually some component in the system will not be able to cope and the system will stop working. This failure may be intermittent (it works most of the time but fails more often than usual) continuous (the system never works at the higher frequency) or, in the worst case, irreversible (a component is damaged by overheating). Improved cooling may be needed to maintain the same level of reliability.Last updated: 2014-07-12
Overdrive
An Intel Pentium processor which fits into a socket designed to accomodate an Intel 486, or into a special upgrade socket on the motherboard.
Last updated: 1995-03-27
overflow
The condition that occurs when the result of a calculation is too big to store in the intended format. For example, the result of adding one to 255 cannot be represented as an unsigned, eight-bit integer. In a signed integer representation, overflow can occur when an integer becomes either too positive or too negative.
Overflow can also occur in the exponent of a floating point number representation. The term "underflow" is sometimes used for negative overflow of the exponent. Ignoring overflow will result in nonsensicle results such as 255 + 1 = 0. At the hardware level, the ALU typically indicates overflow by setting an overflow flag bit which the program can test. Programming languages will typically respond to overflow by raising some kind of signal or other error condition to halt normal execution. Some languages attempt to avoid overflow by providing (optional) variable length number representation (multiprecission arithmetic) so that the maximum number representable is limited only by the amount of storage available.Last updated: 2008-05-30
overflow bit
A processor flag bit set by the ALU to indicate overflow.
Last updated: 2008-05-30
overflow flag
overflow bitoverflow pdl
<jargon>
The place where you put things when your pdl is full. If you don't have one and too many things get pushed, you forget something. The overflow pdl for a person's memory might be a memo pad. This usage inspired the following doggerel:
Hey, diddle, diddle The overflow pdl To get a little more stack; If that's not enough Then you lose it all, And have to pop all the way back. --The Great QuuxThe term pdl seems to be primarily an MITism; outside MIT this term is replaced by "overflow stack".
Last updated: 2008-05-30
overhead
1. Resources (in computing usually processing time or storage space) consumed for purposes which are incidental to, but necessary to, the main one. Overheads are usually quantifiable "costs" of some kind. Examples: The overheads in running a business include the cost of heating the building. Keeping a program running all the time eliminates the overhead of loading and initialising it for each transaction. Turning a subroutine into inline code eliminates the call and return time overhead for each execution but introduces space overheads.2. information, such as control, routing, and error checking characters, that is transmitted along with the user data. It also includes information such as network status or operational instructions, network routing information, and retransmissions of user data received in error.
3. Overhead transparencies or "slides" (usually 8-1/2" x 11") that are projected to an audience via an overhead (flatbed) projector.Last updated: 1997-09-01
overloading
<language>
(Or "Operator overloading"). Use of a single symbol to represent operators with different argument types, e.g. "-", used either, as a monadic operator to negate an expression, or as a dyadic operator to return the difference between two expressions. Another example is "+" used to add either integers or floating-point numbers. Overloading is also known as ad-hoc polymorphism.
User-defined operator overloading is provided by several modern programming languages, e.g. C++'s class system and the functional programming language Haskell's type classes. Ad-hoc polymorphism (better described as overloading) is the ability to use the same syntax for objects of different types, e.g. "+" for addition of reals and integers or "-" for unary negation or diadic subtraction. Parametric polymorphism allows the same object code for a function to handle arguments of many types but overloading only reuses syntax and requires different code to handle different types.Last updated: 2014-01-05
overriding
Redefining in a child class a method or function member defined in a parent class.
Not to be confused with "overloading".Last updated: 1996-12-21
overrun
1. A frequent consequence of data arriving faster than it can be consumed, especially in serial line communications. For example, at 9600 baud there is almost exactly one character per millisecond, so if a silo can hold only two characters and the machine takes longer than 2 milliseconds to get to service the interrupt, at least one character will be lost. 2. Also applied to non-serial-I/O communications. "I forgot to pay my electric bill due to mail overrun." "Sorry, I got four phone calls in 3 minutes last night and lost your message to overrun." When thrashing at tasks, the next person to make a request might be told "Overrun!" Compare firehose syndrome. 3. More loosely, may refer to a buffer overflow not necessarily related to processing time (as in overrun screw). [Jargon File]overrun screw
A variety of fandango on core produced by a C program scribbling past the end of an array (C implementations typically have no checks for this error). This is relatively benign and easy to spot if the array is static; if it is auto, the result may be to smash the stack - often resulting in heisenbugs of the most diabolical subtlety. The term "overrun screw" is used especially of scribbles beyond the end of arrays allocated with malloc; this typically overwrites the allocation header for the next block in the arena, producing massive lossage within malloc and often a core dump on the next operation to use stdio or malloc itself. See spam, overrun; see also memory leak, memory smash, aliasing bug, precedence lossage, fandango on core, secondary damage.Last updated: 1995-01-19
overuse strain injury
<medical>
(Or "repetitive strain injury", RSI, "repetitive strain disorder") Any tendon or muscle injury resulting from overuse, usually in the hand, wrist, or arm. Injury may be caused by any combination of repetitive, unacustomed, or prolonged movements, forcefulness, or an awkward position (often due to bad ergonomics). The symptoms are pain, tingling, weakness, numbness, swelling, cracking, stiffness, or reduced coordination.
Common conditions are: Carpal tunnel syndrome, where swelling of the membrane linings in your wrist surrounding the tendons that bend your fingers compresses the median nerve. This may result in numbness and pain in the hand, arm, shoulder, and neck. Tennis elbow, where rotating your wrist and using force causes a form of epicondylitis. Tendinitis, where unacustomed exercise or repeated awkward movements inflame wrist, elbow, or shoulder tendons, often leading to severe stiffness. Trigger finger, a popping or catching sensation when you bend your finger, wrist, or shoulder. This form of tenosynovitis is caused by repetitive hand movements. To prevent the condition worsening, treat the pain with heat, cold, or aspirin, ibuprofen, or naproxen sodium; rest; or immobilise the injured area with a splint or bandage. See a doctor. Amara's RSI information. RSI links from Yahoo. Guide to Carpal Tunnel Syndrome. CTS from Yahoo.Last updated: 1999-10-03
Nearby terms:
outside-in testing ♦ outsourcing ♦ overclocking ♦ Overdrive ♦ overflow
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