Instruction set of microprocessor: Data transfer, Arithmetic
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.
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.
