In 8085 Instruction set, LDA is a mnemonic that stands for LoaD Accumulator with the contents from memory. In this instructionAccumulatorwill get initialized with 8-bit content from the 16-bit memory address as indicated in the instruction as a16. This instruction uses absolute addressing for specifying the data. It occupies 3-Bytes in the memory. First Byte specifies the opcode, and the successive 2-Bytes provide the 16-bit address, i.e. 1-Byte each for each memory location.
|Mnemonics, Operand||Opcode(in HEX)||Bytes|
Let us consider LDA 4050H as an example instruction of this type. It is a 3-Byte instruction. The initial content of memory address 4050H is ABH. Initially 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 execution of this instruction is as below −
|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 13 T-States for execution as shown in the timing diagram.