Unformatted text preview: in the operation and 1 if register X (the index register) is involved. The register specifier is not color coded. The 2-bit addressing-mode specifier (shaded light blue) says how to interpret the operand part of the instruction. If the addressing mode is 00, the operand is in the operand specifier of the instruction. This addressing mode is called immediate (i). If the addressing mode is 01, the operand is the memory address named in the operand specifier. This addressing mode is called direct (d). (There are two other addressing modes that we do not cover here.) The distinction between the immediate addressing mode and the direct addressing mode is very important because it determines where the data involved in the operation is stored or is to be stored. See Figure 7.3. Locations that contain addresses are shaded in red; operands are shaded gray....
View Full Document
- Fall '10
- Machine code, operand specifier