GDSX (Extended General Device Support) Manual

Overview of GDSX
Extended General Device Support (GDSX) Manual—529931-001
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External Interfaces
is restarted at the instruction following the last type 2 checkpoint call, and all its
memory pool data is preserved.
External Interfaces
There are three standard external interfaces provided by GDSX:
•
The file system interface between TSCODE and business application processes.
•
The file system interface between TSCODE and the IOPs.
•
The SCF/SPI interface.
File System Interface Between TSCODE and Business
Application Processes
GDSX supports the following Guardian file-system calls from external processes:
Refer to the Guardian Procedure Calls Reference Manual for the detailed syntax,
parameter meanings, condition codes, and considerations for each call.
File System Interface Between TSCODE and IOPs
GDSX supports any type of terminal equipment for any vendor, so long as HP provides
the basic access method such as Envoy, TERMPROCESS, SNAX, and so on. GDSX
supports all the system procedure calls that are supported by the I/O processes.
GDSX can issue requests to IOPs according to what is supported by an I/O process;
each call is either preprocessed within GDSX or passed directly to the I/O process.
SCF/SPI Interface
This interface provides two types of access:
•
Conversational input by means of the Subsystem Control Facility (SCF) provided
by HP
Procedure Name Function
CLOSE Closes an open device
CONTROL Performs device-dependent I/O operations
DEVICEINFO Retrieves information about a device or subtype 30 process
OPEN Establishes a communication path between an application process and
a device
SETMODE Sets device-dependent functions
WRITE Writes data from an array in an application program to an open device
WRITEREAD Writes data to a device from an application program, then waits for
data to be transferred back from the device