Absolute addressing mode in 8085 Microprocessor

MicrocontrollerMicroprocessor8085

In this mode, the data is directly copied from the given address to the register. This absolute addressing mode is also called a direct addressing mode. For example LDA 3000H: means the data at address 3000H is copied to register A.

  • LDA 4050H

Let us consider LDA 4050 Has an example instruction of this type. It is a 3-Byte instruction. The initial content of memory address 4050H is ABH. initial accumulator content is CDH. As after execution A will be initialized with value ABH. Memory location 4050H will still remain with the content ABH. The results of the execution of this instruction are as below –

 


Before
After
(4050)
ABH
ABH
A
CDH
ABH



Address
Hex Codes
Mnemonic
Comment
2008
3A
LDA 4050H
A ← Content of the memory location 4050H
2009
50

Low order Byte of the address
200A
40

High order Byte of the address



Here is the timing diagram of the instruction LDA 4050H – 


Summary − So this instruction LDA 4050H requires 3-Bytes, 4-Machine Cycles (Opcode Fetch, Memory Read, Memory Read, Memory Read) and 1

raja
Published on 04-Jan-2019 17:29:40
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