What is ADD B in 8085?
Table of Contents
- 1 What is ADD B in 8085?
- 2 How many T states are required for an 8085 microprocessor to execute the opcode fetch machine cycle?
- 3 What add instructions?
- 4 What is a 1 byte instruction?
- 5 Which byte instruction data transfer instruction LDAX B?
- 6 What are the different types of instructions in 8085 microprocessor?
- 7 How many bytes does the dad b instruction occupy?
What is ADD B in 8085?
In 8085 Instruction set, ADD R is a mnemonic that stands for “Add contents of R to Accumulator”. As addition is a binary operation, so it requires two operands to be operated on….Instruction type ADD R in 8085 Microprocessor.
| Mnemonics, Operand | Opcode(in HEX) | Bytes |
|---|---|---|
| ADD B | 80 | 1 |
| ADD C | 81 | 1 |
| ADD D | 82 | 1 |
| ADD E | 83 | 1 |
How many T states are required for an 8085 microprocessor to execute the opcode fetch machine cycle?
4 T-States
Summary: So this instruction STC requires 1-Byte, 1-Machine Cycle (Opcode Fetch) and 4 T-States for execution as shown in the timing diagram.
What operation is performed during 4 T State of opcode fetch?
During T4 microprocessor performs internal operation like decoding opcode and providing necessary actions. The opcode is decoded to know whether T5 or T6 states are required, if they are not required then µp performs next operation.
What is the addressing mode of LDAX B?
In 8085 Instruction set, LDAX is a mnemonic that stands for LoaD Accumulator from memory pointed by eXtended register pair denoted as “rp” in the instruction. This instruction uses register indirect addressing for specifying the data….Instruction type LDAX rp in 8085 Microprocessor.
| Mnemonics, Operand | Opcode(in HEX) | Bytes |
|---|---|---|
| LDAX B | 0A | 1 |
| LDAX D | 1A | 1 |
What add instructions?
The add instruction adds together its two operands, storing the result in its first operand. The three operand form multiplies its second and third operands together and stores the result in its first operand.
What is a 1 byte instruction?
In 1-byte instruction, the opcode and the operand of an instruction are represented in one byte. A one-byte instruction includes a opcode and a operand in the same byte. If there is no numeral present in the instruction then that instruction will be of one-byte. for example, MOV C, A, RAL, and ADD B, etc.
Which 8085 instruction requires maximum number of T States and how many?
16 T states and 5 machine cycles. It is a 3 byte instruction. It is one of the 256 instructions of 8085 having highest T states. The other instruction is XTHL – Exchange H and L with top of stack.
How many T State are there in opcode fetch machine cycle for the instruction push B?
12 T-States
Summary − So this instruction PUSH B requires 1-Byte, 3-Machine Cycles (Opcode Fetch, Memory Write, Memory Write) and 12 T-States for execution as shown in the timing diagram.
Which byte instruction data transfer instruction LDAX B?
8085 Data-transfer Instructions
| Opcode | Operand | Meaning |
|---|---|---|
| LDAX | B/D Reg. pair | Load the accumulator indirect |
| LXI | Reg. pair, 16-bit data | Load the register pair immediate |
| LHLD | 16-bit address | Load H and L registers direct |
| STA | 16-bit address | 16-bit address |
What are the different types of instructions in 8085 microprocessor?
According to the instruction word size in 8085 microprocessor, there are three types of instructions: They include opcode and operands in the same byte. Operands are internal registers and coded into the instruction. Instructions require one memory location to store the single byte in the memory.
How many instructions are there in an 8-bit instruction?
Instructions require two memory locations to store in the memory. Note: Instructions having the 8-bit number either as an address or data as the operand is 2 – Byte Instructions. In a 3-byte instruction, the first byte specifies the opcode, and the following two bytes specify the 16-bit address.
Is 8085 8-bit or 16-bit?
In spite of the fact that 8085 is an 8-bit microprocessor, but there are some instructions are there available in the 8085 instruction set which can do 16-bit additions also. As the 8085 internal architecture is only 8-bits, this instruction easily takes double the time needed to add two 8-bit numbers.
How many bytes does the dad b instruction occupy?
Let us consider DAD B is a sample instruction of this category. As It is 1-Byte instruction so it occupies a single Byte place in the memory. We are considering the initial content of HL and BC register pairs are 4050H and 4060H.
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