Function:

Halts the processor, CPU restarts only when external event takes place such
as RESET activation, NMI request on NMI lines or maskable interrupt request
on INTR when interrupts are enabled.
Handy to use with following piece of code:

          STI        ; enable interrupts
     lazy:
          HLT        ; suspend CPU internal bus clock
          IN AL,60h  ; Key pressed !
          CMP AL,whatever_key
          JNE lazy   ; was not our key, just go back to sleep.

If the CPU is not going to be used for any processing tasks (hence is idle)
one may execute the code above to cool down the CPU because it stops the
internal CPU bus clock. It also saves (some) energy.





IBTS op1,op2   Insert Bit String
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