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GFK-0467K Chapter 4 Series 90-30/20/Micro Instructions Set 4-161
4
SVCREQ #18: Read I/O Override Status
Use SVCREQ function #18 in order to read the current status of overrides in the CPU.
Note
This feature is available only for 331 or higher CPUs.
For this function, the parameter block has a length of 1 word. It is an output parameter block only.
0 = No overrides are set. address
1 = Overrides are set.
Note
SVCREQ #18 reports only overrides of %I and %Q references.
Example:
In the following example, the status of I/O overrides is always read into location %R1003. If any
overrides are present, output %T0001 is set on.
| _____ _____
|%I0001 | | | |
|——|/|———| SVC_|——————————| EQ_ |–
| | | | |
| | REQ | | INT |
| | | | | %T0001
| CONST —|FNC | CONST —|I1 Q|——————————————————————————————————————————( )—
| 00018 | | 00001 | |
| | | | |
|%R1003 —|PARM | %R1003 —|I2 |
| |_____| |_____|
|