One unit (ALU1) is feature complete, while the other (ALU2) lacks some low usage instructions and therefore can be used more often for tasks like address calculations.
Thus it may perform the effective address calculation from the operand and addressing mode fields of the extracode, before entering the supervisor.
For example, when an instruction required any address calculations, the main CPU would handle them before the 68881 took control.
The address arithmetic unit serves for address calculations.
They are often used to avoid the need for expensive multiplication operations when performing address calculation on an array element.
A hash function controls the address calculation of linear hashing.
Indirektno) - multi-level memory indirect (note: the address is loaded from specified location and, should it also specify "I" flag the indirect address calculation continues
All stack machines have variants of the load/store opcodes for accessing local variables and formal parameters without explicit address calculations.
Spare registers were used to factor out repeated address calculations.
Program correctness is maintained through effective address calculation to prevent hazards through memory.