Immediate And Direct Addressing

Página 1

In order to access anything that is held in memory you need to know its address. The address is a number that tells the computer where in memory to go to find a specific item of data. Data is put into or copied out of memory in different ways using addressing modes. Two of the main addressing modes are:

Direct Addressing: Using a direct address mode tells the CPU which address contains the data you want to access. So LDR r1, 100 would copy the data held in memory location 100 into register 1.

Immediate Addressing: Rather than loading the contents of a memory address, the immediate address method loads the data directly. Therefore, the operand would have to be the actual number that you wish to use. A command such as MOV r1, #10 would move the value 10 into register 1.