control_keys

Apollo

The program can be stopped by typing control-Q.

An interrupt mechanism that will stop the current computation but not the program has not yet been implemented for Apollo.

Control-Z is interpreted as an EOF by the Fortran run time I/O library. Program execution is terminated after this control.

CMS

CMS lacks control keys.

The program can be stopped if necessary by hitting the CP key and then typing IPL CMS. There is no elegant interrupt when a plot is being produced in interactive mode.

The standard EOF mark in VM (a blank return) is intercepted and is treated like a blank input line.

The line separation character (#) is switched off during startup of the program since the symbol has a meaning in Garfield.

Unix

The program can be stopped by typing control-C.

Lengthy loops can be interrupted by checking for the existence of a file. For example, the following loop

For i From 1 To 10000 Do
   If exist(`stop_loop`) Then Leave
   // Lengthy calculation
Enddo

checks each iteration whether a file called "stop_loop" exists and ends the loop iteration if this is the case. To stop the loop, the user would type (to the Unix command prompt):

touch stop_loop

There is currently no elegant built-in interrupt to stop lengthy calculations without terminating program execution.

Control-Z will place the program in the background, you will need to type "bg" in addition to make it continue to run.

Vax

The program can be stopped by typing control-Y.

Control-C on a Vax will terminate execution of the command that is being executed and then return control to the command reading routine. The graphics buffers are emptied if plotting is in progress, to make sure GKS is in a well defined state. The terminal printing buffer is flushed. Other I/O channels are left untouched, hence a dataset attached to logical unit 12 (used for short term sequential dataset access) may be left open. This is harmless since the dataset will be closed when a new dataset has to be opened. The same goes for dataset access that is transparent to the user.

The RTL I/O routines have to be replaced so as to avoid blocking of the terminal I/O channel when the AST occurs in an RTL routine. The reason for this is that AST intercepting routine simply unwinds the stack until the routine which has been LIB$ESTABLISH'ed, usually the command reading routine.

Control-Z is interpreted as an EOF by the Fortran run time I/O library. Program execution is terminated after this control.

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Formatted on 21/01/18 at 16:55.