HP 3000 Manuals HP 3000 Manuals
What Happens When You Enter a Subsystem Break
When more than one process is currently running within your process tree
structure, the CONTROL-Y signal interrupts the last process to arm the
trap.
When a process is interrupted by a CONTROL-Y signal, the following occur:
1. The input/output transactions pending between the process and the
terminal are completed and flagged as though all were completed
successfully.
2. Control is transferred to the trap procedure. This procedure
executes at the same execution level (either privileged or
nonprivileged) as the interrupted user program.
3. Control returns from the trap procedure to the interrupted program
or procedure.
a. If the interrupted program or procedure was waiting for
completion of input/output (reading from or writing to the
terminal) when the CONTROL-Y signal was received, the program
continues execution immediately after the FREAD or FWRITE
call. These intrinsics will indicate successful completion.
b. If the CONTROL-Y signal was received during reading, the
number of characters typed in before this signal is returned
to you as the value of FREAD. The "carriage" position is
unchanged.
If you send another CONTROL-Y signal, it is ignored unless you issued a
call to the RESETCONTROL intrinsic at some point prior to the signal.