Asynchronous Terminals and Printer Processes Programming Manual

TERMINAL PROGRAMMING CONSIDERATIONS
Using Break (Multiple Processes per Terminal)
If BREAK is pressed, the command interpreter receives the break
message.
If each process that uses BREAK keeps track of the previous
owner, break ownership can be passed among any number of
processes in an orderly fashion.
Terminal and File Access Types
SETMODE 11 and SETMODE 12 can specify terminal and file access
types. Terminal access type defines the operations that have
access to the terminal. Break terminal access means that only
file operations that have break access are permitted with the
terminal after BREAK is pressed. Normal terminal access means
that all file operations are permitted.
Break file access is used by applications that own break to
acquire exclusive access to the terminal. Normal file access
allows all applications to access the terminal.
Exclusive Access when BREAK is Pressed
You can use SETMODE 11 and SETMODE 12 to set terminal access type
and file access type so a number of processes can access the same
terminal until the operator presses BREAK. One process can take
exclusive access to the terminal when BREAK is pressed. Do this
in four steps:
1. Enable BREAK with break access type. After the BREAK key
is pressed, only file operations that have break access are
permitted with the terminal.
The following SETMODE operation performs this type of break
monitoring:
operation = 11, set BREAK ownership and terminal
access type
parameter-1 = cpu,pin , enable BREAK for process
cpu,pin
parameter-2 = 1, terminal access type is break
last-parameters = last owner and last terminal access type
on return from SETMODE
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