Instruction Clock Cycle Calculation



	Some instructions require additional clock cycles due to a "Next
	Instruction Component" identified by a "+m" in the instruction
	clock cycle listings.  This is due to the prefetch queue being
	purge on a control transfers.	Below is the general rule for
	calculating "m":


	88/86 not applicable
	286  "m" is the number of bytes in the next instruction
	386  "m" is the number of components in the next instruction
		(the instruction coding (each byte), plus the data and
		the displacement are all considered components)


8088/8086 Effective Address (EA) Calculation


		   Description				  Clock Cycles

	Displacement						6
	Base or Index (BX,BP,SI,DI)				5
	Displacement+(Base or Index)				9
	Base+Index (BP+DI,BX+SI)				7
	Base+Index (BP+SI,BX+DI)				8
	Base+Index+Displacement (BP+DI,BX+SI)		       11
	Base+Index+Displacement (BP+SI+disp,BX+DI+disp)	       12


	- add 4 cycles for word operands at odd addresses
	- add 2 cycles for segment override
	- 80188/80186 timings differ from those of the 8088/8086/80286


	Task State Calculation

	"TS" is defined as switching from VM/486 or 80286 TSS to one of
	the following:

 			|---------------------------------------.
			|	        New Task		|
			|---------------------------------------|
	|---------------|486 TSS|486 TSS|386 TSS|386 TSS|286 TSS|
	|   Old Task	| (VM=0)| (VM=1)| (VM=0)| (VM=1)|	|
	`---------------+-------+-------+-------+-------+-------|
	386 TSS (VM=0)	|	|	|  309  |  226  |  282  |
			|-------+-------+-------+-------+-------|
	386 TSS (VM=1)	|	|	|  314  |  231  |  287  |
			|-------+-------+-------+-------+-------|
	386 CPU/286 TSS	|	|	|  307  |  224  |  280  |
			|-------+-------+-------+-------+-------|
	486 CPU/286 TSS	|  199	|  177	|	|	|  180	|
			`---------------------------------------'

		       	     
	Miscellaneous

	- all timings are for best case and do not take into account wait
	  states, instruction alignment, the state of the prefetch queue,
	  DMA refresh cycles, cache hits/misses or exception processing.
	- to convert clocks to nanoseconds divide one microsecond by the
	  processor speed in MegaHertz:
   

(1000MHz/(n MHz)) = X nanoseconds



	- see	8086 Architecture