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Microprocessor Articles
Page 42 of 42
Instruction type CMP R in 8085 Microprocessor
In 8085 Instruction set, CMP is a mnemonic that stands for “CoMPareAccumulator” and hereR stands for any of the following registers, or memory location M pointed by HL pair. R = A, B, C, D, E, H, L, or M This instruction is used to compare contents of the Accumulator with given register R. The result of compare operation will be stored in the Temp register. Temp is not a GPR (General Purpose Register) but an internal register that is not accessible to the programmer. Actually R register’s content will get subtracted from Accumulators content and difference value ...
Read MoreInstruction type RLC in 8085 Microprocessor
In 8085 Instruction set, there is one mnemonic RLC stands for “Rotate Left Accumulator”. It rotates the Accumulator contents to the left by 1-bit position. The following Fig. shows the operation explicitly. In this fig. it has been depicted that the most significant bit of the Accumulator will come out and left rotate will create an empty space at the least significant bit place and this come out bit will be copied at the empty bit place and also on the Cy bit in the flag register. Thus, Cy flag gets a copy of the bit moved out ...
Read MoreInstruction type RAL in 8085 Microprocessor
In 8085 Instruction set, there is another mnemonic RAL, which stands or Rotate Accumulator Left and also involving Cy flag in rotation. It rotates the Accumulator contents to the left by 1-bit position. The following Fig. is depicting the execution logic of the instruction.From the Fig. we can see that the due to left rotation the bit which is coming out from the most significant place will be copied to the Cy flag bit. And the previous Cy bit will be moved to least significant bit place of the Accumulator. Thus it is a 9-bit rotation of Accumulator and Cy ...
Read MoreInstruction type RRC in 8085 Microprocessor
In 8085 Instruction set, RRC stands for “Rotate Right Accumulator”. With the help of this instruction, we can rotate the Accumulator current content to the right by 1-bit position. The following Fig. will depict the rotation operation. In this right rotation, the least significant bit will come out from the Accumulator and will be copied to Cy bit in the flag register and also will be copied to the most significant bit position of the Accumulator. Notice that the Cy flag is not involved in the rotation, and it is only 8-bit rotation of Accumulator contents. ...
Read MoreInstruction type POP rp in 8085 Microprocessor
In 8085 Instruction set, with the mnemonic POP, we can pop out 2-Bytes from the top of the stack through rp i.e. register pair e.g. BC, DE, HL or AF. Here AF is a register pair formed with Flag and Accumulator registers and also known as PSW (Processor Status Word). In PSW, Accumulator is the MS Byte, and Flags register is the LS Byte. Mnemonics, Operand Opcode(in HEX) Bytes POP B C1 1 POP D D1 1 POP H E1 1 POP PSW F1 1 In the above ...
Read MoreInstruction type PUSH rp in 8085 Microprocessor
In 8085 Instruction set, PUSH rp instruction stores contents of register pair rp by pushing it into two locations above the top of the stack. rp stands for one of the following register pairs. rp = BC, DE, HL, or PSW As rp can have any of the four values, there are four opcodes for this type of instruction. It occupies only 1-Byte in memory. Mnemonics, Operand Opcode(in HEX) Bytes PUSH B C5 1 PUSH D D5 1 PUSH H E5 1 PUSH PSW F5 1 ...
Read More8085 program to move blocks of bits from source location to a destination location
Problem Statement − Move a block of 16 data stored from 8050H to 805FH to a target location from 8070F to 807FH. Address Hex Codes Label Mnemonic T-States Comment 8000 21 50 80 START: LXI H, 8050H 10 Setup HL pair as a pointer for source memory. 8003 11 70 80 LXI D, 8070H 10 Set up DE pair as a pointer for destination memory 8006 06 10 MVI B, 10H 7 Set up B to count 16 bytes 8008 7E LOOP: MOV A, M 7 Get ...
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