From Intellivision Wiki
|Instruction Name||Software Interrupt|
|CP1610 Clock Cycles||6|
Intended to generate a software interrupt. According to the GI documentation, this instruction generates a pulse on the Program Counter Inhibit/Trap (PCIT) pin of the CP1610 CPU. It is currently unclear if the instruction has any other behavior, useful or not. In the Intellivision, this instruction apparently has little or no use, as the Intellivision does not connect the CPU's PCIT pin to anything else, and no game uses this opcode.
where: x is ignored