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

The 5028 Operator Station (Figure 9-1) serves as the I/O device for operator communicationwith the system. In addition, it is used for initial program load (IPL) of the systemfrom paper tape and for program preparation.The operator station has a paper tape reader, a keyboard, and special control keys toenter data and control information. The operator station includes a paper tape punch anda printer to receive output from the system. Information is transferred from the system tothe operator station at the rate of 10 characters per second. Information is transferred tothe system from the paper tape reader at the rate of 10 characters per second. The rate atwhich information is transferred to the system from the keyboard varies according to theoperator, the operating program, and the mechanical characteristics of the keyboard. It is,therefore, less than 10 characters per second.A program-controlled bell in the operator station can be used to audibly alert theoperator. The bell rings once each time a unique character code (hex 87) is transmittedto the operator station.Graphics on the operator station keyboard and printer use the American Standard Codefor Information Interchange (ASCII code) as listed in Appendix D. However, all 256 binarycombinations can be punched into paper tape and read from it.The printer uses 8-1/2-inch-wide (21,6 cm) roll paper. Characters are printed 10 perinch with a maximum of 72 characters per line horizontally, and 6 lines per inch vertically.The printer is equipped with a sensing device to detect a low paper supply. When thisoccurs, following a print command, condition code 0 is returned and indicator bit 15 inthe interrupt status word is set on.The printing mechanism in the operator station automatically returns to the left marginafter 72 characters have been printed. If a print command is directed to the operator stationwhile the carriage is returning, the character may print in the middle of the page duringcarriage movement. To prevent this, the program should count the characters printed on anyline and issue a carriage return command followed by a line feed command when the carriageapproaches the end of the printing line. The carriage return and line feed commands shouldbe in that order to give the carriage enough time to return to the left margin.The tape punch uses one-inch-wide (2,54 cm) paper or Mylar* tape. Data is representedby eight character bits as shown in Figure 9-2. The tape punch is equipped with a sensingdevice to detect a low tape supply. When this occurs, following a punch command, conditioncode 1 is returned and the DCC status word bit 3 is set on.*Trademark of E.I. du Pont de Nemours & Co. (Inc.)