What is an Opcode?

What is an Opcode?
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Answer :

The part of the instruction that specifies the operation to be performed is called the Operation code or opcode.
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Related questions

Computer instructions written with the use of English words instead of binary machine code is called a. Mnemonics b. Symbolic code c. Gray codes d. Opcode

Description : Computer instructions written with the use of English words instead of binary machine code is called a. Mnemonics b. Symbolic code c. Gray codes d. Opcode

Last Answer : b. Symbolic code

Instruction in computer languages consists of a. OPCODE b. OPERAND c. Both of above d. None of above

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In 8085 microprocessor, how many T-states does OPCODE FETCH machine cycle normally require

Description : In 8085 microprocessor, how many T-states does OPCODE FETCH machine cycle normally require (i.e., when HOLD and WAIT signals are NOT forced)? A) 4 to 6 B) 3 to 8 C) 2 to 3 D) 8 to 12 

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What are the four parts of label , opcode , operand and comment ?

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Two important fields of an instruction are. a. Opcode b. Operand c. Only a d. Botha&b

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Last Answer : b. Processors

Opcode is the machine instruction obtained from decoding instruction stored in. a. Stack pointer b. Address pointer Cc. Instruction register d. Incrementer

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The operation is specified by a binary code known as the a. Operand code b. Opcode c. Source code d. — Allof these

Description : The operation is specified by a binary code known as the a. Operand code b. Opcode c. Source code d. — Allof these

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Computer instructions written with the use of English words instead of binary machine code is called a. Mnemonics b. Symbolic code c. Gray codes d. Opcode

Description : Computer instructions written with the use of English words instead of binary machine code is called a. Mnemonics b. Symbolic code c. Gray codes d. Opcode

Last Answer : b. Symbolic code

Explain ALIGN & ASSUME

Description : Explain ALIGN & ASSUME

Last Answer : The ALIGN directive forces the assembler to align the nextsegment at an address divisible by specified divisor. The format is ALIGN number where number can be 2, 4, 8 or 16. Example ALIGN 8. The ASSUME ... the segment registers at execution time. Example ASSUME CS: code, DS: data, SS: stack

What is linker

Description : What is linker

Last Answer : A linker is a program used to join together several object files into one large object file. For large programs it is more efficient to divide the large program modules into ... & debugged. When all the modules work they are linked together to form a large functioning program.

What is loader

Description : What is loader

Last Answer : The loader copies the program into the computer’s main memory at load time and begins the program execution at execution time.

What is assembler

Description : What is assembler

Last Answer : The assembler translates the assembly language program text which is given as input to the assembler to their binary equivalents known as object code. The time required to translate the assembly code ... time. The assembler checks for syntax errors & displays them before giving the object code.

How does the microprocessor differentiate between data and instruction

Description : How does the microprocessor differentiate between data and instruction

Last Answer : When the first m/c code of an instruction is fetched and decoded in the instruction register, the microprocessor recognizes the number of bytes required to fetch the entire ... will be considered as data & the byte after the data will be treated as the next instruction.

What is Microcontroller and Microcomputer

Description : What is Microcontroller and Microcomputer

Last Answer : Microcontroller is a device that includes microprocessor; memory and I/O signal lines on a single chip, fabricated using VLSI technology. Microcomputer is a computer that is designed using microprocessor as its CPU. It includes microprocessor, memory and I/O.

Why do we use XRA A instruction

Description : Why do we use XRA A instruction

Last Answer : The XRA A instruction is used to clear the contents of the Accumulator and store the value 00H.

Define stack and explain stack related instructions

Description : Define stack and explain stack related instructions

Last Answer : The stack is a group of memory locations in the R/W memory thatis used for the temporary storage of binary information during the execution of the program. The stack related instructions are PUSH & POP

What is the use of bi-directional buffers?

Description : What is the use of bi-directional buffers?

Last Answer : It is used to increase the driving capacity of the data bus. The data bus of a microcomputer system is bi-directional, so it requires a buffer that allows the data to flow in both directions.

What is the use of addressing modes, mention the different types

Description : What is the use of addressing modes, mention the different types

Last Answer : The various formats of specifying the operands are called addressing modes, it is used to access the operands or data. The different types are as follows • Immediate addressing • Register addressing • Direct addressing • Indirect addressing • Implicit addressing

Explain the different instruction formats with examples

Description : Explain the different instruction formats with examples

Last Answer : The instruction set is grouped into the following formats • One byte instruction MOV C,A • Two byte instruction MVI A,39H • Three byte instruction JMP 2345H

Explain LDA, STA and DAA instructions

Description : Explain LDA, STA and DAA instructions

Last Answer : LDA copies the data byte into accumulator from the memory location specified by the 16-bit address. STA copies the data byte from theaccumulator in the memory location specified by 16-bit address. DAA changes the contents of the accumulator from binary to 4-bit BCD digits.

Mention the categories of instruction and give two examples for each category

Description : Mention the categories of instruction and give two examples for each category

Last Answer : The instructions of 8085 can be categorized into the following five • Data transfer MOV Rd,Rs STA 16-bit • Arithmetic ADD R DCR M • Logical XRI 8-bit RAR • Branching JNZ CALL 16-bit • Machine control HLT NOP

Explain the signals HOLD, READY and SID

Description : Explain the signals HOLD, READY and SID

Last Answer : HOLD indicates that a peripheral such as DMA controller is requesting the use of address bus, data bus and control bus. READY is used to delay the microprocessor ... slow responding peripheral is ready to send or accept data. SID is used to accept serial data bit by bit

How many machine cycles does 8085 have, mention them

Description : How many machine cycles does 8085 have, mention them

Last Answer : The 8085 have seven machine cycles. They are • Opcode fetch • Memory read • Memory write • I/O read • I/O write • Interrupt acknowledge • Bus idle

What is the use of ALE

Description : What is the use of ALE

Last Answer : The ALE is used to latch the lower order address so that it can be available in T2 and T3 and used for identifying the memory address. During T1 the ALE goes high, the latch is transparent ... is the lower order address. When ALE goes low the lower order address is latched until the next ALE.

What is an instruction?

Description : What is an instruction?

Last Answer : An instruction is a binary pattern entered through an input device to command the microprocessor to perform that specific function

Define instruction cycle, machine cycle and T-state

Description : Define instruction cycle, machine cycle and T-state

Last Answer : Instruction cycle is defined, as the time required completing theexecution of an instruction. Machine cycle is defined as the time required completing one operation of accessing memory, I/O or ... request. Tcycle is defined as one subdivision of the operation performed in one clock period

Basic concepts in memory interfacing

Description : Basic concepts in memory interfacing

Last Answer : The primary function of memory interfacing is that the microprocessor should be able to read from and write into a given register of a memory chip. To perform these operations the microprocessor ... Be able to select the chip Identify the register Enable the appropriate buffer

How many interrupts does 8085 have, mention them

Description : How many interrupts does 8085 have, mention them

Last Answer : The 8085 has 5 interrupt signals; they are INTR, RST7.5, RST6.5, RST5.5 and TRAP

Steps involved to fetch a byte in 8085

Description : Steps involved to fetch a byte in 8085

Last Answer : i. The PC places the 16-bit memory address on the address bus ii. The control unit sends the control signal RD to enable the memory chip iii. The byte from ... byte is placed in the instruction decoder of the microprocessor and the task is carried out according to the instruction

What are operations performed on data in 8085

Description : What are operations performed on data in 8085

Last Answer : The various operations performed are • Store 8-bit data • Perform arithmetic and logical operations • Test for conditions • Sequence the execution of instructions • Store data temporarily during execution in the defined R/W memory locations called the stack

What is the signal classification of 8085

Description : What is the signal classification of 8085

Last Answer : All the signals of 8085 can be classified into 6 groups • Address bus • Data bus • Control and status signals • Power supply and frequency signals • Externally initiated signals • Serial I/O ports

What is a microcomputer?

Description : What is a microcomputer?

Last Answer : A computer that is designed using a microprocessor as its CPU is called microcomputer.

Explain priority interrupts of 8085.

Description : Explain priority interrupts of 8085.

Last Answer : The 8085 microprocessor has five interrupt inputs. They are TRAP, RST 7.5, RST 6.5, RST 5.5, and INTR. These interrupts have a fixed priority of interrupt service. If two or more interrupts go ... 8085 is shown in the table. Interrupts Priority TRAP RST 7.5 RST 6.5 RST 5.5 INTR

What is meant by interrupt?

Description : What is meant by interrupt?

Last Answer : Interrupt is an external signal that causes a microprocessor to jump to a specific subroutine.

What is meant by polling?

Description : What is meant by polling?

Last Answer : Polling or device polling is a process which identifies the device that has interrupted the microprocessor.

List the four instructions which control the interrupt structure of the 8085 microprocessor.

Description : List the four instructions which control the interrupt structure of the 8085 microprocessor.

Last Answer : • DI ( Disable Interrupts ) • EI ( Enable Interrupts ) • RIM ( Read Interrupt Masks ) • SIM ( Set Interrupt Masks )

What is meant by Wait State?

Description : What is meant by Wait State?

Last Answer : This state is used by slow peripheral devices. The peripheral devices can transfer the data to or from the microprocessor by using READYinput line. The microprocessor remains in wait state as long as READY ... contents of the address, address/data and control buses are held constant.

Control signals used for DMA operation are ____________

Description : Control signals used for DMA operation are ____________

Last Answer : HOLD & HLDA.

How many address lines in a 4096 x 8 EPROM CHIP?

Description : How many address lines in a 4096 x 8 EPROM CHIP?

Last Answer : 12 address lines.

What is the difference between the shift and rotate instructions?

Description : What is the difference between the shift and rotate instructions?

Last Answer : A rotate instruction is a closed loop instruction. That is, the data moved out at one end is put back in at the other end. The shift instruction loses the data that is moved out of the last bit locations.

Explain the purpose of the I/O instructions IN and OUT.

Description : Explain the purpose of the I/O instructions IN and OUT.

Last Answer : The IN instruction is used to move data from an I/O port into the accumulator. The OUT instruction is used to move data from the accumulator to an I/O port. The IN & OUT instructions are used only on microprocessor, which use a separate address space for interfacing.

Explain the difference between a JMP instruction and CALL instruction.

Description : Explain the difference between a JMP instruction and CALL instruction.

Last Answer : A JMP instruction permanently changes the program counter. A CALL instruction leaves information on the stack so that the original program execution sequence can be resumed.

List out the five categories of the 8085 instructions. Give examples of the instructions for each group.

Description : List out the five categories of the 8085 instructions. Give examples of the instructions for each group.

Last Answer : • Data transfer group – MOV, MVI, LXI. • Arithmetic group – ADD, SUB, INR. • Logical group –ANA, XRA, CMP. • Branch group – JMP, JNZ, CALL. • Stack I/O and Machine control group – PUSH, POP, IN, HLT.

How many operations are there in the instruction set of 8085 microprocessor?

Description : How many operations are there in the instruction set of 8085 microprocessor?

Last Answer : There are 74 operations in the 8085 microprocessor.

What is an Operand?

Description : What is an Operand?

Last Answer : The data on which the operation is to be performed is called as an Operand.