1.15 O


OCR (Optical Character Recognition) - Images of text are scanned in, and the computer will try to interpret it, much as a human who is reading a page would. These systems are not perfect, and often rely on spell checkers, and other tricks to achieve reliabilities up to 99%


octal - a base 8 numbering system that uses the digits 0 to 7.


Octave - a doubling of frequency


odd parity - a bit is set during communication to indicate when the data should have an odd number of bits.


OEM (Original Equipment Manufacturer) -


off-line - two devices are connected, but not communicating.


offset - a value is shifted away or towards some target value.


one-shot - a switch that will turn on for one cycle.


on-line - two devices are put into communications, and will stay in constant contact to pass information as required.


opcode (operation code) - a single computer instruction. Typically followed by one or more operands.


open collector - this refers to using transistors for current sourcing or sicking.


open loop - a system that does monitor the result. open loop control systems are common when the process is well behaved.


open-system - a computer architecture designed to encourage interconnection between various vendors hardware and software.


operand - an operation has an argument (operand) with the mnemonic command.


operating system - software that existing on a computer to allow a user to load/execute/develop their own programs, to interact with peripherals, etc. Good examples of this is UNIX, MS-DOS, OS/2.


optimization - occurs after synthesis and after a satisfactory design is created. The design is optimized by iteratively proposing a design and using calculated design criteria to propose a better design.


optoisolators - devices that use a light emitter to control a photoswitch. The effect is that inputs and outputs are electrically separate, but connected. These are of particular interest when an interface between very noisy environments are required.


OR - the Boolean OR function.


orifice - a small hole. Typically this is places in a fluid/gas flow to create a pressure difference and slow the flow. It will increase the flow resistance in the system.


oscillator - a device that produces a sinusoidal output.


oscilloscope - a device that can read and display voltages as a function for time.


OSF (Open Software Foundation) - a consortium of large corporations (IBM, DEC, HP) that are promoting DCE. They have put forth a number of popular standards, such as the Motif Widget set for X-Windows programming.


OSHA (Occupational safety and Health Act) - these direct what is safe in industrial and commercial operations.


OSI (Open System Interconnect) - an international standards program to promote computer connectivity, regardless of computer type, or manufacturer.


overshoot - the inertia of a controlled system will cause it to pass a target value and then return.


overflow - the result of a mathematical operation passes by the numerical limitations of the hardware logic, or algorithm.