Each instruction has a one-byte (8-bit) operation codes or opcode. With 8- bit binary opcode, a total of different operation codes can. Intel instruction set. x0, x1, x2, x3, x4, x5, x6, x7, x8, x9, xA, xB, xC, xD, xE, xF. 0x, NOP 1 4 , LXI B,d16 3 10 , STAX B 1 7 , INX B 1 6 –K 1 1 ADDRESSING MODES OF Shown in the following are the sizes of a 5CH This can be verified from the opcode chart given in the previous chapter.
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Store 8-bit data in cyart Program 1: The result of both programs will be the same. In program 1 direct addressing instruction is used, whereas in program 2 indirect addressing instruction is used.
Exchange the contents of memory locations Statement: Exchange the contents of memory locations Cart and H. In Program 1, direct addressing instructions are used, whereas in Program 2, indirect addressing instructions are used. Add two 8-bit numbers Statement: Add the contents of memory locations H and H and place the result in memory location H.
Subtract the contents of memory location H from the memory location H and place the result in memory location H. Subtract two 8-bit numbers Sample problem: Add the bit number in memory locations H and H to the bit number in memory locations H and H. The most significant eight bits of the two numbers to be added are in memory locations H and H.
Store 8-bit data in memory
Store the result in memory locations H and H with the most significant byte in memory location H. Store I6-bit result in memory locations H and H. Terminate program execution NOTE: In program 2, bit addition instruction DAD is used. Add contents of two memory locations Statement: Add the contents of memory locations H and H and place the result in the memory locations Hand H.
Programs For Microprocessor Learners
Subtract the bit number in memory locations H and H from the bit number in memory locations H and H. The most significant eight bits of the two numbers are in memory locations H and H. Pack the two unpacked BCD numbers stored in memory locations H and H and store result in memory location H.
Assume the least significant digit is stored at H. Two digit BCD number is stored in memory location H.
Opcodes of 8085 Microprocessor
Read the program given below and state the contents of all registers after the execution of each instruction in sequence. Write hcart program to shift an eight bit data four bits right. Assume data is in register C. Write a program to shift a 16 bit data, 1 bit right.
Assume that data is in BC register pair. Program to shift a bit data 1 bit left. Write a set of instructions to alter the contents of flag register in