Instruction set of microprocessor: Data transfer, Arithmetic

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1. Unit-II-A Instruction Set and programming with 8085 Assembly Language programming basics, Instruction set of microprocessor: Data transfer, Arithmetic, logical, loop, branching etc, timing diagram, writing, assembling and executing assembly language programs.

2. Flag register of 8085

3. S-Sign flag  - After the execution of arithmetic or logical operations, if bit D7 of the result is 1, the sign flag is set. In a given byte if D7 is1, the number will be viewed as a negative number. If D7 is U, the number will be considered as a positive number. Z-Zero flag  -The zero flag sets if the result of the operation in ALU is zero and flag resets if the result is non zero. The zero flags are also set if a certain register content becomes zero following an increment or decrement operation of that register.

4. Data Transfer Instructions Move or copy data from one location to another. Examples: MOV, MVI, LXI, STA, LDA. Logical Instructions Execute bit-wise logical operations such as AND, OR, XOR, and comparison. Examples: ANA, ORA, CMP, XRA.

5. Branching Instructions Change the flow of program execution based on conditions or unconditionally. Examples: JMP, CALL, RET, JNZ. Control Instructions Control operations like interrupt handling and halting the processor. Examples: HLT, NOP, RIM, SIM.

6. AC-auxiliary Carry flag  - This flag is set if there is an overflow out of bit 3 i.e. carry from lower nibble to higher nibble (D3 bit to D4 bit). This flag is used for BCD operations and it is not available for the programmer. P-Parity flag   -   Parity is defined by the number of ones present in the accumulator. After arithmetic or logical operation, if the result has an even number of ones, i.e.even parity, the flag is set. If the parity is odd, the flag is reset. CY-Carry flag  - This flag is set if there is an overflow out of bit 7. The carry flag also serves as a borrow flag for subtraction. In both the examples shown below, the carry flag is set.