GDSX (Extended General Device Support) Manual

DEVICE^HANDLER Example, Running and
Managing
Extended General Device Support (GDSX) Manual—529931-001
4-9
Running an Application Process
Figure 4-3 illustrates the processing that occurred up to this point. The GDSX process,
named $GDS, performed its initialization processing and issued a READUPDATE on
$RECEIVE. Then the application program, named $A1, performed its initialization
processing and issued a call to OPEN $GDS.#TC1. $GDS received the open
message and in turn issued an OPEN $TC1, which was processed by the IOP.
$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.
Figure 4-3. Initial Message Flow
Initialization:
READUPDATE
$RECEIVE
Initialization:
OPEN $GDX.#TCI
OPEN $TCI
IOP opens device
Process OPEN
completion; reply
with completion code
READUPDATE
WRITEREAD
prompt, "CPU, PIN-"
Do datastream
conversion;
WRITEREAD prompt
WRITE "CPU, PIN-"
and read input text
VST014.vsd
$A1
IOP/Terminal
$GDS