I&C SCI 51 Lecture Notes - Lecture 14: Operand, Memory Address, Direct Mode

• School: UC-Irvine
• Department: Information and Computer Science
• Course: I&C SCI 51
• Professor: Shannon Alfaro

Document Summary

Primarily looking at the trade-offs b/w opcodes and addresses. There are many ways to specify addresses, these are called addressing modes. In this type, the operand itself is included rather than the operand itself. The number of values is limited by the size of the field. In this method, an operand is specified by directly giving its full memory address. The instruction will always access the same memory location: used to access global variables who address is known as compile time. Since many programs have global variables this method is widely used o. In this mode, the operand being specified either comes from memory or goes to memory but its address is not hard-wired into the instruction as the direct mode. The address is instead in a register, an address used in this manner is called a pointer. So, pretty much memory can be referenced without having a full memory address in the instruction.