In bisynchronous communications, a positive acknowledgment character used to indicate that a message was received correctly.
Refers to data represented by a physical variable that varies in a continuous rather than discrete manner and is usually represented by an electrical signal.
Acronym for American National Standards Institute, Inc. ANSI establishes standards for transmission codes and protocols.
Software that performs a specific application or task, such as word processing, accounting, or financial planning in contrast to a utility or system program that is used to carry out file management and housekeeping functions during or in conjunction with applications software tasks.
In SNA, VTAM communicates with many applications. The APPLID is the identifying name of a VTAM application.
Acronym for American Standard Code for Information Interchange. The standard specifies the correspondence between 128 graphic and control symbols to a 7-bit code.
A communications technique in which each character is transmitted as a discrete unit. The character transmitted is preceded by a start bit and followed by one or more stop bits. As each character is bracketed by start and stop bits, varying amounts of time can exist between characters. Contrasts with synchronous communication. Also called start-stop communications.
A procedure for making a duplicate copy of data for use if the primary data are lost or destroyed.
A PC DOS file that contains a sequence of DOS commands. You enter the name of the batch file on the keyboard; PC DOS then executes all the commands stored in the batch file as if typed from the keyboard.
The number of changes in line condition per second. The term is commonly used as a measure of speed of information transmission expressed in bits-per-second. The use of baud to mean bits-per-second is valid for the RS232 side of the modem.
See bisynchronous communication (BSC).
In SNA communications, operation in which the host and remote Logical Units (LUs) initiate a session and agree upon the protocol to be used within that session.
A low-level data-link line protocol for synchronous communications first used by IBM. It only supports half-duplex communications.
The name of an elementary unit of information that has two states. Usually the two states are called 0 and 1.
A contiguous vector of bits that is read or written as a unit.
At start-up of a computer system, the first record read from disk contains a program used to read the remainder of the operating system into memory. The first record read is called the bootstrap program.
Abbreviation for bits-per-second. A unit of measure for the rate that information is transferred.
Acronym for binary synchronous communication.
An area of computer memory that is used for performing input or output operations. Data are read into a buffer or written from a buffer.
The name of an 8-bit group.
Eighty consecutive characters of information, or one line.
Characters used to control vertical spacing of print lines.
The large computer that has data bases, communications networking control, and large computing and memory capacity.
A common parallel interface for printers. Developed by Centronics Corporation.
Direct method of attaching printers to S/370 mainframes.
A single letter, digit, symbol, space, or punctuation mark.
In SNA communications, commands in character form entered by an end user. These commands, such as LOGON and LOGOFF, must be in the syntax defined in the user’s unformatted system services definition table. Also known as unformatted.
An electrical signal that occurs at a fixed rate. It is used to control the speed of other circuits. In synchronous communications both send and receive data have a clocking signal.
A heavily shielded and insulated carrier wire with high immunity to electrical interference and a low data error rate. Coax is capable of carrying multiple streams of data on one line. This is the same cable commonly used in the cable TV industry.
Asynchronous serial port 1 on the PC.
Something you instruct the computer to do, such as run a program.
A specification of data and control message formats and their meanings. This specification is followed by both the sender and receiver in a communication link.
A communications device that controls the transmission of data over lines in a network. Types of control units are transmission control units and communication controllers.
A communication control unit that manages line control and data transfer through a network. Operations are controlled by one or more programs stored and executed in the unit. Examples are the IBM 3705, 3725, and 3745 communication controllers.
In SNA communications, to increase throughput in data transmission, two bytes are sent as one byte. The receiver decompacts the data to the original two bytes.
Programs that convert instructions written in high-level languages to the machine language that the computer can interpret.
To increase throughput in data transmission, one character is substituted for a sequence of duplicate blanks and two characters for a sequence of non-blank characters. The receiver decompresses the data to their original state.
RJE Console.
A specific combination of hardware that forms a system. When talking about the IBM PC, the term configuration describes characteristics such as the type of monitor adapter, the number and description of printers, the amount of memory, and description of serial ports.
The device used to control the operation of a computer, including a keyboard and display or printers.
Any character used to facilitate transmission of data between the PC and the host.
See communication control unit.
Abbreviation for central processing unit. The component of a computer system that performs instruction sequencing, logic and arithmetic, and controls input/output. In a microcomputer, this is a single chip.
Cyclical redundancy check that catches all one-, two-, and three-bit errors in a sequence.
A representation of facts, concepts, or instructions in a formalized manner suitable for communication, interpretation, or processing by human or automatic means.
Communication rules for the orderly exchange of information between two nodes on a data link. The lowest level protocol of SNA and BSC.
The Dataproducts interface, which originated with the Dataproducts Corporation, is used for driving high-speed printers and typesetting equipment.
Acronym for Direct Access Vertical Forms Unit. A control sequence of characters used to define a vertical print form. The DAVFU convention was first established by Dataproducts Corporation.
See leased line.
The reverse operation of modulate. Transforming an analog signal into the digital information it represents.
The input and output unit connected to the computer such as printer, plotter, and monitor.
A number that uniquely names a device.
A telephone line connected to the switched telephone network where the destination is selected by dialing a multi-digit number. Also called a switched line or a dial line. Opposite of leased line or dedicated line.
The termination of a physical connection.
A flexible magnetic-coated mylar disk used to record information. Synonymous with flexible disk or floppy disk.
A TV-like device used to display information.
IBM Personal Computer Disk Operating System. (See PC DOS).
IBM Disk Operating System for the S/370 class of computers.
A DOS S/370 operating systems program that simultaneously operates many readers, printers, and remote communications devices.
Acronym for Extended Binary-Coded Decimal Interchange Code. The standard specifies the correspondence between 256 graphic and control symbols to an 8-bit code. The code was first used with the IBM System/360.
Systematic alteration of data which prevents unauthorized persons from viewing and using the data.
One to three characters following the file name after the period. Example: STUDY5.JOB
Acronym for Forms Control Buffer Load. A record sent from a host to a remote to specify vertical forms control.
Acronym for Federal Communications Commission.
Transfer of files between two computer systems.
In SNA communications, 8-bit character used to introduce and end SDLC transmission frame. It is coded in binary 01111110.
Mechanism used to meter output to devices (printers) so that data are not sent faster than they can be accepted. See also pacing and virtual route pacing.
In SNA communications, logon that is coded into fields for remote name, password, LOGMODE table, and APPLID.
In SNA communications, a consecutive string of bits that are sent as a unit. The frame begins with a flag followed by an address and control byte, data, and cyclical redundancy check (CRC), and ends with a flag.
Describes a communications link that allows for the simultaneous transmission of data in both directions (in contrast to half-duplex).
The 40 key options—F1 through F10, SHIFT+F1 through SHIFT+F10, CTRL+F1 through CTRL+F10, and ALT+F1 through ALT+F10—on the left or top of the keyboard.
A device that uses protocol conversion to connect dissimilar communications systems. BARR/SNA RJE and BARR/HASP each serve as a gateway between a local area network and a mainframe.
Symbols that are represented by a picture in contrast to ones with an alphabetic name such as carriage return.
Describes a communications link that only allows for transmission of data in one direction at a time (in contrast to full-duplex).
The physical components in a computer system. Examples: processor, memory, display, and printer. These are the hard components of a computing environment as opposed to the soft information components that include programs and data processed by the computer.
Acronym for Houston Automatic Spooling Priority system. A popular enhancement to the IBM operating system that was used for many years as a job entry system for both local readers and printers as well as RJE terminals.
Data at the start of a file.
A notation for writing numbers that employs base 16. The digits in this notation are 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, C, D, E, F.
See central host computer.
Acronym for International Business Machines Corporation.
Acronym for International Business Machines Personal Computer.
Acronym for International Business Machines Personal System/2.
In SNA communications, identification data used for dial-up devices.
Information that is read into a computer.
Process in which the RJE description of the PC is specified.
The connection between any two components in a system. The term is used for the connection between both software and hardware components.
Mechanism used to stop a program for an event needing immediate attention.
Abbreviation for input/output. This represents data transfer between a mainframe and peripheral equipment.
Acronym for Job Control Language. A language interpreted by the operating system.
Acronyms for Job Entry Subsystems of the IBM MVS operating system. These subsystems are used for entering jobs into the MVS operating system and dispensing the output from the jobs. JES2 and JES3 are replacements for the HASP II program that was used for this same purpose.
An independent unit of work processed by the central host operating system. The job includes Job Control Language statements, programming language statements, and data to be processed. The output of a job includes printed output and updates to files on disk or tape.
Abbreviation for kilobyte.
A small device that plugs into the computer’s parallel port. The printer cable attaches to the other end of the key. Used for software protection, it must be placed on LPT1. The key is provided by Barr with the BARR/SNA RJE (TRN) software.
A unit of computer memory that is 1,024 bytes. Each byte is eight bits long. 1,024 in decimal notation is the same as 10000000000 in binary notation. The kilo prefix means times 1,024 in computer literature.
See local area network.
A language consists of a set of symbols, the rules that define what sequences of symbols are syntactically correct, and the meanings attached to various parts of the language. Some languages include FORTRAN, C, COBOL, ALGOL, English, and French.
A communications link provided by the telephone company that is dedicated for use by one customer. It is also called a private line service and may be a privately owned cable between two points.
Connection between one computing unit and another computing unit. These units may be a central host computer and a remote terminal. In this manual, the line usually refers to a line coming out of a communications controller that is connected to a modem by an RS232 cable.
The number of binary digits that can be sent over a communication line in one second. Line speed is expressed as bits per second (bps).
A recording of the frames sent and received on a communication line.
A high-speed communications network. Typically several PCs are linked together, and the network is usually restricted to a single building or campus.
In SNA communications, an independent stream of data that is multiplexed with other streams within a physical unit.
In SNA communications, a description of a type of session. This description is used at the time sessions undergo the bind operation. This is usually the definition of the remote terminal.
In SNA communications, to terminate a session.
In SNA communications, to initiate a session or to initiate a session between an application program and a logical unit.
In SNA communications, a logical unit sends a message in response to logon. This entire logon sequence or message is the logon data.
A testing procedure in which transmitted data are returned as received data.
Parallel printers 1, 2, and 3 of the PC.
An instruction in a source language that points to a sequence of instructions in the same language to replace it. The macro can also specify values for parameters in the replacement instructions.
Term used for a large central computer that offers a full set of computing services. The term originated in the days when the central processor, memory, and input/output channels were located in one central housing called the mainframe.
The longest unit of information transmitted as a consecutive series of bits. In asynchronous communication, a message is a single character. In synchronous communication, a message is a block of characters preceded by some sync characters and terminated by some end-of-block marker.
See multiple logical unit RJE.
In SNA communications, the macro that defines the LOGMODE table.
In SNA communications, table of LOGMODE definitions.
Modulate/Demodulate. A device designed to interface between a digital communication link and an analog communication link. Usually the digital communication link is a computer or terminal. The analog communication link is usually a telephone line. Modulate is to convert a digital signal from the computer into an analog signal capable of being transmitted by the telephone system. Demodulate is the opposite of modulate.
In HASP communications, a communications protocol that allows for one communications link to send data in both directions at the same time. In each direction multiple streams of data can flow to several printers or disk files. It uses the BSC (binary synchronous communication) data link protocol.
In SNA communications, the most sophisticated RJE protocol supported by SNA. It enables several logical units to simultaneously send and receive multiple streams of data.
See multiple logical unit RJE.
To concentrate multiple streams of data on one medium.
In SNA and 3780 communications, a line that has more than one physical unit communication with the central host computer. These physical units share the line with only one sending on the line at one time. Also known as multidrop line.
A centrally located unit to which token ring nodes are connected. The MAU repairs the ring by removing non-functioning nodes from the ring, thus maintaining the integrity of the ring even if there is a malfunction.
Acronym for Multiple Virtual Storage operating system. A large IBM operating system that operates on System/370, 3081, and 3091 processors.
In bisynchronous communications, a negative acknowledgment character used to indicate a problem with receiving a message.
In SNA communications, a program that controls the operation of a communication controller. It is generated by the user from a library of IBM-supplied modules.
Acronym for Network Basic Input/Output System, a standard interface between PC software and LAN adapters such as Token Ring, Ethernet, or ARCNET adapters.
In bisynchronous communications, an obsolete standard that does not allow transmission of all 256 characters.
See leased line.
In SNA communications, a method of coding data transmission so that the sender changes the signal for a binary 0 to the opposite state and leaves the signal for binary 1 in the same state. Also known as invert on zero coding.
Device that deletes output.
Disconnected from system. Processing that is performed in isolation.
Connected to system. Processing that is performed during direct communications between a workstation and a computer.
A JES2 command used to modify the verb or the command or identify the job or system facility to be acted upon.
A master program that manages the resources of the computer. The operating system provides a set of services to all programs for input/output, data management, program loading, memory allocation, and communication facilities for job entry and output dispatching.
Commands sent to the central host.
Acronym for Operating System.
Written information from the computer.
In SNA communications, controls the flow of data to the remote from VTAM.
A device interface to the computer that reads and writes groups of bits at the same time. A common way for printers to be connected to the IBM PC.
A variable that is given a constant value for a specified application.
A bit appended to a group of binary digits to assure that the sum of bits is either even or odd. This serves as an error-detection scheme for data communications.
The operating system supported by IBM on the IBM PC.
Acronym for Pulse Code Modulation code. A coding scheme used for the digital transmission of telephone calls. The analog telephone signal is sampled 8,000 times a second. For each sample an 8-bit code is constructed. This digital code is sent within the telephone system. The 8-bit code is converted back to the analog signal prior to being put on the local telephone line.
Appendages to the computer that serve as memory, sources of information, or are controlled by the computer. Peripheral devices include disk drives, printers, and communications devices such as modems.
In SNA communications, an independent unit attached to an SDLC line.
Output from central host that is to be written to a graphics plotter device.
RJE printer 1.
Data used to specify operating mode of printer.
Commands sent to the host to manage printing of special forms.
A program or processor attached to a local area network that manages file printing.
Capability for managing the printing of files on one or more printers.
A disk used in daily operation of the PC.
A set of instructions that gives step-by-step details of how to complete a task. For a computer, the instructions can be written in a high-level language like FORTRAN, BASIC, or PASCAL. Instructions in a form directly usable by the computer are called machine language instructions.
See communications protocol.
Translation between two computer protocols (such as Async and SNA RJE) so that two dissimilar systems can communicate.
RJE punch device 1.
Output from the central host computer that consists of a file of lines up to 80 characters long.
A list of items waiting for service in a system.
The source of lines entered into the central computer by an RJE workstation. These lines usually make up a job that is run on the central computer.
To obtain data from a communications line (in contrast to send).
Options that control the manner in which files are received.
A terminal attached via a communications link to a central computer.
Acronym for Remote Job Entry. A computing environment in which you can create programs and data offline on the PC, transmit to the mainframe, receive the printouts at high speed on diskette or printers, and control the status of jobs by using remote operator commands.
Refers to EIA Standard RS232C for connecting data communication equipment to data terminal equipment, including the connection of terminals and computers to modems. Many computer peripheral devices also use this interface for connection to the computers. See serial interface port.
Acronym for Remote Spooling Communications Subsystem. A remote job entry system of the IBM VM operating system that is compatible with BARR/HASP.
IBM mainframe machine architecture. See also channel attach.
Acronym for Synchronous Data Link Control, a low-level communications protocol for synchronous communications. It is defined for both full-duplex and half-duplex operation. SNA uses SDLC as its low-level communications protocol.
Interface ports that send and receive data one bit at a time using the RS232 standard.
Files read from serial port COM1 and sent to the host.
SNA communications between two logical units that start with a logon and end with a logoff.
In HASP communications, command sent to terminate a terminal session.
In HASP communications, a file of data that signals the mainframe computer to end communications with your PC.
In HASP communications, the process of the terminal identifying itself to a central host computer with the central host granting access.
Acronym for Systems Network Architecture. SNA is IBM’s formal definition of its communications network. SNA describes a multilayered communications environment that usually uses SDLC as its lowest level communications protocol.
Refers to the programmable instructions for operating the physical machinery of a computer system. Examples: programs, data bases, and files (in contrast to the hardware components such as the processor, printer, and disk drive).
Start-of-header character of the bisynchronous communications protocol.
Acronym for Simultaneous Peripheral Operations On-Line. Spooling denotes a system that allows several independent flows of data to proceed concurrently. For example, files can be sent from disk to the central computer while other files are being printed. See also print spooling.
In SNA communications, a focal point within an SNA network for managing session services for end users of the network. This includes the configuration, coordinating network operator and problem determination requests, and providing directory support.
A set of rules established by an industry or governmental organization. Usually implies an extensive review process.
See dial-up line.
Character sent before a bisynchronous communications protocol message or block.
Communications adapter that allows connection to a synchronous modem.
Mode of communication in which blocks of characters are sent as a unit without start and stop bits for each character. Unlike asynchronous communication, the timing for data is obtained from the carrier signal and is not a function of time-from-the-start bit.
A character that causes advancement of the printer to a tab stop.
The end of a communication line. A simple terminal is a keyboard and a TV-like display. More powerful terminals include disk storage, a computer, printers, and plotters.
An elapsed time period without a transmission or other expected event occurring.
An interface adapter installed in the 3745 or 3725 to connect to a Token Ring Network.
High-speed communication network that consists of physical equipment and architecture. This is the IBM architecture for local area networks. The network is characterized by ring structure with a single token continuously circling the ring.
Process of converting from one coding convention to another.
To send data from one place to another for reception.
A variation of binary synchronous communication that allows transmission of all 256 characters.
Transmission in the reverse direction, that is, reversal from send to receive or from receive to send. This usually refers to a half-duplex communication channel.
Parameters that assist in easy operation of BARR/SNA RJE and BARR/HASP.
Trademark of TYMNET, Inc., an international data communications network.
No glossary entries.
A super-minicomputer made by Digital Equipment Corporation.
Specification for spacing of lines on print form.
In SNA communications, pacing used to control data flow of the application and VTAM.
Acronym for IBM’s Virtual Machine operating system. A popular operating system for interactive computing. It creates a computing environment in which every user appears to have his/her own IBM 370 computer.
An IBM operating systems program that resides on the mainframe controlling SNA communications between the mainframe applications software and the remote terminals.
No glossary entries.
In SNA communications, an SDLC command and response passed between host and remote that provides initial identification of the remote to the host. Contains IDNUM and IDBLK data.
A control character used to restore (XON) or suspend (XOFF) the flow of data.
No glossary entries.