IBM 847651U Handbook - Page 338

O OBI. Options by IBM. operating system. Software that controls the execution of programs and that may provide services such as resource allocation, scheduling, input/output control, and data management. Although operating systems are predominantly software, partial hardware implementations are possible. (T) P p-type semiconductor. A semiconductor doped with acceptor impurities that, when energized, generates a predominance of positive charge carriers (holes). Contrast with n-type semiconductor. See also PMOS. P-type semiconductors have a lower level of conductivity than n-type semiconductors and have slower switching rates, but allow higher-density packing of components. P-type and n-type semiconductor materials are often layered together to obtain a rectifying action between the two dissimilar materials. parallel port. An access point through which a computer transmits or receives data that consists of several bits sent simultaneously on separate wires. Contrast with serial port. parity bit. A check bit appended to an array of binary digits to make the sum of all the binary digits, including the check bit, always odd or always even. (A) PCI. Peripheral component interconnect. performance. One of the two major factors, together with facility, on which the total productivity of a system depends. Performance is largely determined by a combination of throughput, response time, and availability. physical. (1) Pertaining to actual implementation or location as opposed to conceptual content or meaning. (A) (2) Contrast with logical. (A) pin. One of the conducting contacts of an electrical connector. PMOS. Positive-channel metal oxide semiconductor. packet. In data communication, a sequence of binary digits, including data and control signals, that is transmitted and switched as a composite whole. The data, control signals, and possibly error control information are arranged in a specific format. (I) port. An access point for data entry or exit. (Contrast with connector.) positive metal oxide semiconductor (PMOS). Positive-channel metal oxide semiconductor. A technology used in field effect transistors that utilize the properties of a p-type semiconductor material, usually 304 Netfinity 3000 User's Handbook