CRC. See cyclic redundancy check CRC | IBM 16/4 Token-Ring instruction

CPU. Central processing unit.

CRC. See cyclic redundancy check (CRC).

CSD. corrective service diskette.

cable segment. A section of cable between components or devices on a network. A segment may consist of a single patch cable, multiple patch cables connected together, or a combination of building cable and patch cables connected together. See LAN segment, ring segment.

computer architecture. The organizational structure of a computer system, including hardware and software.

configuration. (1) The arrangement of a computer system or network as defined by the nature, number, and chief characteristics of its functional units. More specifically, the term may refer to a hardware configuration or a software configuration. (2) The devices and programs that make up a system, subsystem, or network. See also system configuration.

connect. In a LAN, to physically join a cable from a station to an access unit or network connection point. Contrast with attach.

control block. (1) A storage area used by a computer program to hold control information. (2) In the IBM Token-Ring Network, a specifically formatted block of information provided from the application program to the Adapter Support Interface to request an operation.

cyclic redundancy check (CRC). Synonym for frame check sequence (FCS).

data rate. See data transfer rate, line data rate.

data transfer rate. The average number of bits, characters, or blocks per unit of time passing between equipment in a data-transmission session. The rate is expressed in bits, characters, or blocks per second, minute, or hour.

default. Pertaining to an attribute, value, or option that is assumed when none is explicitly specified.

default value. A value assumed when no value has been specified.

device driver. The code needed to attach and use a device on a computer or a network.

diagnostics. Modules or tests used by computer users and service personnel to diagnose hardware problems.

DLS. DOS LAN Services

DOS. See IBM Personal Computer Disk Operating System (DOS).

duplex. In data communication, pertaining to a simultaneous two-way independent transmission in both directions. Synonymous with full-duplex. Contrast with half-duplex.

EISA. Extended Industry Standard Architecture.

enabled. (1) On a LAN, pertaining to an adapter or device that is active, operational, and able to receive frames from the network. (2) Pertaining to a state of a processing unit that allows the occurrence of certain types of interruptions. (3) Pertaining to the state in which a transmission control unit or an audio response unit can accept incoming calls on a line.

FCS. See frame check sequence (FCS)

frame. (1) The unit of transmission in some LANs, including the IBM Token-Ring Network and the IBM PC Network. It includes delimiters, control characters, information, and checking characters. On a token-ring network, a frame is created from a token when the token has data appended to it. On a token bus network (IBM PC Network), all frames including the token frame contain a preamble, start delimiter, control address, optional data and checking characters, end delimiter, and are followed by a minimum silence period. (2) A housing for machine elements. (3) In synchronous data link control (SDLC), the vehicle for every command, every response, and all information that is transmitted using SDLC procedures. Each frame begins and ends with a flag.

frame check sequence (FCS). (1) A system of error checking performed at both the sending and receiving station after a block check character has been accumulated. (2) A numeric value derived from the bits in a message that is used to check for any bit errors in transmission. (3) A redundancy check in which the check key is generated by a cyclic algorithm. Synonymous with cyclic redundancy check (CRC).

FTP. File Transfer Protocol.

full-duplex. Synonym for duplex.

group address. In a LAN, a locally administered address assigned to two or more adapters to allow the adapters to copy the same frame. Contrast locally administered address with universally administered address.

IBM 16/4 Token-Ring manual CRC. See cyclic redundancy check CRC, Full-duplex. Synonym for duplex