Page:CTSS programmer's guide.djvu/36

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 * parameter list.) It is not possible to input to a program the codes for which there are blanks in the column labelled "7090 program input."
 * output from the user program
 * The character or control function corresponding to logical case 0 and the 6-bit code in the column under the appropriate console is typed out. If for a code there is no character or control function indicated in the column labelled "7090 program output," the code will be ignored; for uniformity and future compatibility, it is recommended that the standard "ignore" code be used if this effect is desired.
 * }
 * output from the user program
 * The character or control function corresponding to logical case 0 and the 6-bit code in the column under the appropriate console is typed out. If for a code there is no character or control function indicated in the column labelled "7090 program output," the code will be ignored; for uniformity and future compatibility, it is recommended that the standard "ignore" code be used if this effect is desired.
 * }

Special Input Modes
To anticipate noisy console lines, especially for future remote or dialed connections, a confirmation mode will be available. In this mode, every input message (i.e., up to the break character) will immediately be copied back as an output message. If a user detects a garble he should issue a quit signal or take whatever action he has anticipated in his program.

When a person is working closely with his console at the command level, it will be possible to enter a brief mode. All programs which have been properly prepared will be able to interrogate the brief mode status indicator and to adjust the verbosity of their output accordingly. Both the brief and confirmation modes are set by the use of a command.

Interconsole Messages
Any user console can send a message to another user console by subroutine calls to the supervisor. These messages are placed in an input message pool for the receiving user along with the user number of the sender. The receiving user program can read its message pool at any time by a supervisor call similar to that for reading its own input console; an input-wait status can occur if no messages are present. If a receiver fails to read or acknowledge a message this is assumed to be 22