Prerequisite – Addressing Modes
1. PC relative addressing mode:
PC relative addressing mode is used to implement intra segment transfer of control, In this mode effective address is obtained by adding displacement to PC.
EA = PC + Address field value PC = PC + Relative value
2. Base register addressing mode:
Base register addressing mode is used to implement inter segment transfer of control. In this mode effective address is obtained by adding base register value to address field value.
EA = Base register + Address field value PC = Base register + Relative value
Difference between PC Relative And Base Register Addressing modes:
|PC Relative Addressing Mode||Base Register Addressing Mode|
|The content of program counter is added to the addressing field of the instruction i to obtain the effective address.||The base register content is added to the addressing field of the instruction to obtain the effective address.|
|The addressing field of the instruction is mostly a signed number which can be either positive or negative.||A base register holds a base address and the addressing field of the instruction gives displacement according to the base address.|
|A program counter always keeps track of the instructions of the program stored in its memory.||A particular register has to be selected from the register set, according to the instruction.|
|Uses more bits as it has to specify a memory address directly.||Uses less bits as it has to select a register from a register set.|
|A program counter always contains the address of the immediately next instruction to be executed. After fetching the address mentioned in the instruction, the program counter value immediately increases.||In Base Register addressing mode the displacement value can be the same as the value required to reference the desired address as it does not immediately go to the next instruction.||Effective address of the operand is obtained by adding the program counter content to the addressing field of instruction.||Effective address of the operand is obtained by adding the base register content to the addressing field of instruction.||EA = PC + Address field value
PC = PC + Relative value
|EA = Base register + Address field value
PC = Base register + Relative value
Don’t stop now and take your learning to the next level. Learn all the important concepts of Data Structures and Algorithms with the help of the most trusted course: DSA Self Paced. Become industry ready at a student-friendly price.
- Difference between Memory based and Register based Addressing Modes
- Difference between Indirect and Immediate Addressing Modes
- Difference between Direct and Immediate Addressing Modes
- Difference between Direct and Indirect Addressing Modes
- Difference between Indirect and Implied Addressing Modes
- Difference between Direct and Implied Addressing Modes
- Addressing Modes
- Addressing modes in 8085 microprocessor
- Addressing modes in 8086 microprocessor
- Difference between Register Mode and Register Indirect Mode
- 8085 program to access and exchange the content of Flag register with register B
- Difference between Implied addressing mode and Immediate addressing mode
- Difference between Register and Memory
- What is the difference between fopen modes “r+”, "rw+" and “w+” in PHP?
- 8085 program to exchange content of HL register pair with DE register pair
- Difference between Relative and Absolute Deadline of Real-time Task
- Difference between Simplex, Half duplex and Full Duplex Transmission Modes
- Difference between Static variables and Register variables in C
- Difference between Base class and Derived class in C++
- Register Transfer Language (RTL)
If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to email@example.com. See your article appearing on the GeeksforGeeks main page and help other Geeks.
Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.