A.5.115 HLT: Halt Processor
HLT ; F4 [8086,PRIV]
HLT puts the processor into a halted state, where it will perform no
more operations until restarted by an interrupt or a reset.
On the 286 and later processors, this is a privileged instruction.
This instruction, when supported, generally causes the CPU to idle,
either by sleeping a certain amount of time, releasing a time slice in
a multitasker, or actually halting until the next hardware interrupt
occurs. Thus, executing HLT within an input loop after not receiving any
new inputs allows to idle the system.
DPMI environments may fault when trying to execute HLT, if the host does
not support this usage. Calls such as interrupt 2Fh with AX=1680h must
be used instead then.