These bits enable or disable paired-single execution based on how
they're set. If PSE isn't set, then all paired-single instructions are
illegal. If PSE is set, but LSQE isn't set, then psq_l, psq_lu, psq_st
and psq_stu are illegal to execute.
Also thanks go out to my roommate @Veegie for letting me use his Wii as
a blasting ground for tests, since mine isn't on hand right now. It only
caught on fire twice and only burned down half of the house through the
process; what a team player.
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