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80286 BASE ARCHITECTURE

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Figure 2-12. Use of Memory Segmentation

2.4.3.3 MEMORY MODE

Two modes are !.!sed for simple scalar operands located in memory:

Direct Address Mode. The offset of the operand is contained in the instruction as the displacement element. The offset is a 16-bit quantity.

Register Indirect Mode. The offset of the operand is in one of the registers SI, DI, or BX. (BP is excluded; if BP is used as a stack frame base, it requires an index or displacement component to reference either parameters passed on the stack or temporary variables allocated on the stack. The instruction level bit encoding for the BP only address mode is used to specify Direct Address mode. See Chapter 12 for more details.)

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