Effective Address (EA) Calculations
This table lists the number of clock cycles required to calculate the
effective address on the 8088 microprocessor. The 80x8x processors
require considerably fewer clock cycles to calculate effective
addresses, so this table represents the worst-case.
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EA Component 8088 Clocks Example
Displacement 6 MOV AX,ADDR
Register indirect 5 MOV AX,[BP]
BX, BP, SI, DI
Displacement + Base or Index 9 MOV AX,ADDR[BP]
BX + Disp, BP + Disp
SI + Disp, DI + Disp
Base + Index
BP + DI, BX + SI 7 MOV AX,[BP+DI]
BP + SI, BX + DI 8 MOV AX,[BX+DI]
Displacement + Base + Index
BP + DI + Disp 11 MOV AX,ADDR[BP+DI]
BX + SI + Disp
BP + SI + Disp 12 MOV AX,ADDR[BP+SI]
BX + DI + Disp
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Notes: Add 2 clocks for segment overrides
Each memory reference requires an additional 4 clock
cycles. The Transfers field in the instruction
timing charts gives the number of memory references
for each instruction.
This page last updated on Fri Nov 30 10:49:50 MSK 2001
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