IBM System/7 Functional Characteristics - All about the IBM 1130 ...

Multiple area stations (2791 and/or 2793) attach to the transmission loop by insertinga one-byte shift register in series with the line. This shift register (Figure 14-2) enablesthe area station to examine and modify a full byte of information before passing it on tothe next area station in the loop. Multiple 2795/2796/2797 Data Entry Units, 1035 BadgeReaders, 2798 Guidance Display Units, and 1053 Printers can be connected to each areastation. The maximum distance between any two area stations on the loop, and betweenthe first/last area station and the 2790 Control, is governed by the type of wire used.See Appendix B in the manual IBM 2790 Data Communication System: InstallationManual—Physical Planning, Order No. GA27-3017. Remote locations may be servicedvia a remote loop attached through a 2792 pair.Programming and storage requirements to support the 2790 system limit the actualconfiguration of area stations and associated input and output units that may be attachedto the loop. These limits are specified in manuals that describe programming support forthe particular system using the programs. Programming support is provided for up to four2790 Control Features in a System/7 configuration.For more detailed information on the capabilities, components, features, and applicationsof the 2790 Data Communication System, refer to the manuals IBM 2790 DataCommunication System Component Description, Order No. GA27-3015, and IBM 2790System Summary, Order No. GA27-3016.FromtransmissionloopBypassTotransmissionloop1 1 1 1 1 1 11 byte shift regjParity bitArea stationFigure 14-2. One-byte shift registerIBM 5013 Digital I/O Module Model Al 14-13