GDSX Manual

DEVICE^HANDLER Example, Running and
Managing
Extended General Device Support (GDSX) Manual–134303
4-9
Running an Application Process
$GDS then processed the OPEN completion and called REPLY with a completion code,
indicating whether the application’s OPEN for $GDS.#TC1 was successful. After
checking the condition code, the application program issued a WRITEREAD to
$GDS.#TC1, writing the prompt containing its own CPU number and PIN. $GDS
scanned the prompt text for lowercase alphabetic characters (and in this case found
none) to be converted to uppercase before issuing a WRITEREAD of the converted text
to $TC1. Finally, the IOP wrote the prompt to the screen and waited for input.
At the first application terminal, enter a short text string followed by a carriage return.
The string of characters should then be displayed in reverse order. In addition,
lowercase alphabetic characters should now appear as uppercase, indicating that the
intermediate GDSX process has done its datastream conversion. Figure 4-4 illustrates
the message flow for this transaction.
Figure 4-3. Initial Message Flow
$A1 $GDS IOP/Terminal
Initialization;
READUPDATE
$RECEIVE
Initialization;
OPEN $GDS.#TCI
OPEN $TCI
IOP opens device
Process OPEN
completion; reply
with completion code
WRITEREAD
prompt, "CPU, PIN-"
READUPDATE
Do datastream
conversion;
WRITEREAD prompt
WRITE "CPU, PIN-"
and read input text
CDT004