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An opcode is an instruction. An operand is information used by the opcode. Not all opcodes require operands.

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The microprocessor uses an opcode fetch cycle for every instruction because it has to know the opcode in order to execute it, and that is located in memory.

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3 for opcode fetch, 1 for opcode decode, 3 for operand fetch, and 3 for opcode store, for a total of 10, not including wait states.

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Hi, The equation to find the number of instructions with n-bit opcode is 2^n. If your opcode is n=4, the it's 2^4 which is 16. So with a four bit opcode you can have 16 different instructions. ---- 11 levels

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The process of transferring instruction codes from memory location to instruction queue register is called opcode fetch.

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mov H , L mov is opcode H L are operands

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The instruction opcode is a type of data contained in memory, pointed to by the PC (Program Counter) register.

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IP is incremented after fetch of instruction opcode. Specifically, IP is incremented by the number of opcode bytes.

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Each mnemonic maps directly to a machine instruction code, known as an opcode. Some mnemonics map to more than one opcode, however the instruction's operand types will determine which specific opcode will be generated.

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The 8086 microprocessor differentiates between an opcode and an operand primarily through the instruction format, where the opcode is always specified first, followed by the operands. The opcode indicates the operation to be performed, while the operands represent the data or addresses on which the operation will act. The instruction's length is variable, and the processor uses specific bits in the instruction to determine the types and sizes of operands, allowing it to interpret the instruction correctly. Additionally, the opcode itself can include information about the addressing mode, further aiding in the distinction between opcodes and operands.

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The opcode for a traffic light controller typically depends on the specific microcontroller or programming environment being used. In general, it involves a series of instructions that control the timing and sequence of the lights (red, yellow, green). For example, in a simple assembly language, the opcode might include instructions for setting timers, changing output states, and looping through light sequences. To find the exact opcode, you would need to refer to the documentation for the specific hardware or programming language you are using.

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As far as the bus interface is concerned, there is no real difference between data and instructions. Except for the S0 pin, an opcode fetch will look the same as a memory read. There is one extra clock cycle following an opcode fetch, which is used by the CPU to decode and process the opcode, but the bus does not care because there is no sequence initiation with ALE.

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An opcode, or operational code, is a part of machine language instructions that specifies the operation to be performed by the computer's CPU. It typically represents a specific command, such as addition, subtraction, or data movement. Opcodes are encoded in binary and are crucial for the execution of programs, as they dictate how the processor interprets and executes the instructions. Each opcode corresponds to a unique machine-level operation defined by the CPU architecture.

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The hard way: Download the processor manuals and code the opcode and operands by hand

The easy way: Use an assembler program. The instructions are slightly different for each program, so try reading the manuals.

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In the 8085 microprocessor, the opcode fetch machine cycle is not sufficient on its own for executing the MOV MA instruction. While the opcode fetch cycle is responsible for retrieving the instruction from memory, additional machine cycles are required to perform the data transfer or execution of the instruction. Specifically, the MOV MA instruction involves both an opcode fetch cycle and a memory access cycle to complete the operation. Therefore, multiple machine cycles are necessary for executing this instruction effectively.

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i) Instruction code deals only with mnemonics and its corresponding opcode but data code refers to your data like 10h which is always of 8 bits or a particular address say 8080h which is of 16 bits.

ii) Data is your input to the instruction but an opcode is native to your machine.

iii) Data is user specific instruction while opcode is machine specific instruction

iv) You can alter data code but you cannot modify an instruction opcode.

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the opcode is fetched from the memory and decoded

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In the 8085, the LDA instruction loads the accumulator from memory, while the STA instructionstores the accumulator to memory. LDA is a read, while STA is a write. LDA is opcode 3AH, while STA is opcode 32H.

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In the 8085, the LDA instruction loads the accumulator from memory, while the STA instruction stores the accumulator to memory. LDA is a read, while STA is a write. LDA is opcode 3AH, while STA is opcode 32H.

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an opcode (operation code) is the portion of a machine language instruction that specifies the operation to be performed. Their specification and format are laid out in the instruction set architecture of the processor in question (which may be a general CPU or a more specialized processing unit). Apart from the opcode itself, an instruction normally also has one or more specifiers foroperands (i.e. data) on which the operation should act, although some operations may have implicit operands, or none at all. There are instruction sets with nearly uniform fields for opcode and operand specifiers, as well as others (the x86architecture for instance) with a more complicated, varied length structure.

by: HerLoyd

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LDA is an Intel 8085 opcode, 3AH, that loads that accumulator from a location specified in memory.

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RST is simply the opcode chosen to represent the Restart instruction.

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The OUT instruction on the 8085 uses 10 T cycles, 3 for opcode fetch, 1 for opcode decode, 3 for port address fetch, and 3 for port data store. Any wait states encountered are above and beyond that.

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An opcode is a single instruction in assembly language. An operand is the data it does something with.

For example, in "MOV r0, #0C", MOV is the opcode ("move this value into this register"), while r0 (register 0) and #0C (the number 12) are operands.

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The IR is a register constisting of two parts, opcode and address. The opcode is decoded and gives instructions to the control unit whilst the address part is used to give the location in the memory of for example data required for a certain process

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The 8086/8088 instruction queue is a buffer that holds opcode bytes that have been prefetched by the bus interface unit. This speeds up operations of the processor by helping to reduce fetch latency, i.e. to improve the probability that an opcode byte fetched by the processor is already available.

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#include

#include

#include

void main()

{

char opcode[10],operand[10],label[10],code[10][10],ch;

char mnemonic[10][10]={"START","LDA","STA","LDCH","STCH","END"};

int locctr,start,len,i=0,j=0;

FILE *fp1,*fp2,*fp3;

clrscr();

fp1=fopen("INPUT.DAT","r");

fp2=fopen("SYMTAB.DAT","w");fp3=fopen("OUT.DAT","w");

fscanf(fp1,"%s%s%s",label,opcode,operand);

if(strcmp(opcode,"START")==0)

{

start=atoi(operand);

locctr=start;

fprintf(fp3,"%s\t%s\t%s\n",label,opcode,operand);

fscanf(fp1,"%s%s%s",label,opcode,operand);

}

else

locctr=0;

while(strcmp(opcode,"END")!=0)

{

fprintf(fp3,"%d",locctr);

if(strcmp(label,"**")!=0)

fprintf(fp2,"%s\t%d\n",label,locctr);

strcpy(code[i],mnemonic[j]);

while(strcmp(mnemonic[j],"END")!=0)

{

if(strcmp(opcode,mnemonic[j])==0)

{

locctr+=3;

break;

}

strcpy(code[i],mnemonic[j]);

j++;

}

if(strcmp(opcode,"WORD")==0)

locctr+=3;

else if(strcmp(opcode,"RESW")==0)

locctr+=(3*(atoi(operand)));

else if(strcmp(opcode,"RESB")==0)

locctr+=(atoi(operand));

else if(strcmp(opcode,"BYTE")==0)

++locctr;

fprintf(fp3,"\t%s\t%s\t%s\n",label,opcode,operand);

fscanf(fp1,"%s%s%s",label,opcode,operand);

}

fprintf(fp3,"%d\t%s\t%s\t%s\n",locctr,label,opcode,operand);

fcloseall();

printf("\n\nThe contents of Input Table :\n\n");

fp1=fopen("INPUT.DAT","r");

ch=fgetc(fp1);

while(ch!=EOF)

{

printf("%c",ch);

ch=fgetc(fp1);

}

printf("\n\nThe contents of Output Table :\n\n\t");

fp3=fopen("OUT.DAT","r");

ch=fgetc(fp3);

while(ch!=EOF)

{

printf("%c",ch);

ch=fgetc(fp3);

}

len=locctr-start;

printf("\nThe length of the program is %d.\n\n",len);

printf("\n\nThe contents of Symbol Table :\n\n");

fp2=fopen("SYMTAB.DAT","r");

ch=fgetc(fp2);

while(ch!=EOF)

{

printf("%c",ch);

ch=fgetc(fp2);

}

fcloseall();

getch();

}

INPUT FILE:

INPUT.DAT

** START 2000

** LDA FIVE

** STA ALPHA

** LDCH CHARZ

** STCH C1

ALPHA RESW 1

FIVE WORD 5

CHARZ BYTE C'Z'

C1 RESB 1

** END **

-Fabianski Benjamin

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op code is used as the value of instruction . And operand is address location where the instruction can meet.

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By the opcode. E9 - JMP Direct, EB - JMP Short

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That's what opcode 'NEG' does on some processors.Can be emulated with a 'NOT' and an 'INC'.

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no.it is not necessary because one can make timing 010

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Intel designed the 8085 as a 8 bit computer, with the opcode byte as the first byte of the instruction. As such, there are only 256 possible values for the first opcode byte. (28 = 256) As implemented, Intel provided only 83 different instructions.

It is possible, however, in general, that secondary opcode space be usable, so the "8 bit" rule might not necessarily apply, but Intel chose to not implement any of them on the 8085, like they did on the 8086/8088.

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Yes and no. INTR response requires an opcode fetch sequence from the interrupting hardware device, often a CALL instruction, so there is no vector table in memory for it, because you can CALL any location. On the other hand, some implementations provide an RST instruction as the opcode, making it a vectored interrupt.

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That's already been done. Its called a DEC PDP-8.

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To write object code for a format 2 instruction in the SIC/XE machine, you need to identify the opcode for the instruction and the registers involved. The object code consists of the 8-bit opcode followed by the 4-bit binary representation of the two registers. The format is typically structured as follows: the first 8 bits for the opcode, the next 4 bits for the first register, and the last 4 bits for the second register. Finally, you concatenate these binary values to produce the final object code.

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To calculate the number of machine cycles and opcode fetches for any instruction, you need to refer to the architecture's documentation, which outlines the instruction set and the corresponding cycles for each instruction. Typically, an opcode fetch counts as one machine cycle, and the total machine cycles for an instruction will depend on its complexity and any additional operations it requires, such as data fetches or memory accesses. Analyze the instruction's microarchitecture to determine the number of cycles needed for its execution, including any potential delays or dependencies.

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A microprocessor know whether the next byte is an instruction or data because the microprocessor knows for what it is looking. The bus, on the other hand, for an 8085 based system, knows an opcode from data by looking at S0 and S1 when IO/M- is low. If both are high, it is an opcode, otherwise it is data.

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from what ive seen yes. Centsports is a free online sports betting site: http://www.centsports.com/?opcode=351728

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Three for opcode fetch, one for decode, two to process the manipulation of the stack pointer.

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A code that leaves a spare bit to indicate that if that bit is set, consider this byte and the next byte to be defining the entire code.

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The instruction IN 84H in the 8085 microprocessor requires 5 machine cycles to complete. This includes 1 opcode fetch cycle and 4 memory read cycles. The opcode fetch retrieves the instruction from memory, while the read cycles are used to read the data from the specified input port.

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The 8086 microprocessor differentiates between opcodes and instruction data through its instruction format, where the first byte(s) typically represent the opcode, while subsequent bytes represent operands or data. The opcode specifies the operation to be performed, while the data can include registers, memory addresses, or constants. Additionally, the instruction pointer and segment registers help the processor understand the context of the instruction, allowing it to interpret the opcode and associated data correctly. This structured format enables the 8086 to efficiently decode and execute instructions.

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The opcode field occupies 6 bits in a microprocessor to provide a balance between the number of distinct instructions that can be represented and the overall complexity of the instruction set. With 6 bits, a microprocessor can encode up to 64 different opcodes, allowing for a diverse range of operations while keeping the instruction decoding logic manageable. This design choice helps optimize performance and resource utilization in the processor architecture. Additionally, the limited opcode space allows for efficient implementation of common instructions while reserving space for future expansions.

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The STA 4200H instruction in the 8085 requires 4 machine cycles and 13 T states to complete its fetch, processing, and execution.

Cycle One: Opcode fetch, 3 T states plus one opcode process state.

Cycle Two: Opcode address byte 00H fetch, 3 T states

Cycle Three: Opcode address byte 42H fetch, 3 T states

Cycle Four: Accumulator store, 3 T states.

Each cycle will have additional T-Ready states as needed by the READY pin. 13 T states is the minimum.

The LDA instruction will also require 13 T states, with the last cycle being a read cycle instead of a write cycle.

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The 8086/8088 instruction queue is a buffer that holds opcode bytes that have been prefetched by the bus interface unit. This speed up operations of the processor by helping to reduce fetches latency, i.e. to improve the probability that an opcode byte fetched by the processor is already available.

This works best when there is no branching, as a branch would invalidate the queue. Advanced processors attempt to "predict" the branch, making the probability even better.

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Immediate addressing mode is when one of the operands is "immediately" located after the opcode. It is more correct to say that the operand is part of the instruction.

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Immediate addressing mode is when one of the operands is "immediately" located after the opcode. It is more correct to say that the operand is part of the instruction.

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It is partial with opcode and processor code. It is meaningless when we see it on our eyes, but it provides info instructions to Java Virtual Machine to execute that.

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