äNOP
No operation
äCan
be used to fill in code areas to start instructions on word boundaries
äCan
be used to control timing in a loop
äHLT
Halt, to stop execution until:
äA
pulse is sent to the reset line
äOr
an interrupt occurs
äUseful
for debugging
äLOCK
äUsed
to synchronize operations when multiple processors
äProvides
support for semaphores that can be used to provide mutual exclusion over hardware resources