Each instruction in an assembly program has the following fields : (i) Lable field Please write the proper sequence of fields :
(ii) Operand field
(iii) Comment field
(iv) Mnemonic field
(i), (iv), (ii) & (iii)
An assembly statement reads left to right as label, mnemonic, operand, comment — (i), (iv), (ii), (iii), option 2.
LOOP: MVI A, 05H ; load 5 into A
| Field | In the example | Purpose | Optional? |
|---|---|---|---|
| (i) Label | LOOP: | Names the address, for jumps and calls | Yes |
| (iv) Mnemonic | MVI | The operation — assembles to the opcode | No |
| (ii) Operand | A, 05H | What the operation acts on | Depends |
| (iii) Comment | ; load 5 into A | Explanation for the reader | Yes |
The order is not arbitrary; each field's position follows from its job. The label must come first because it marks the address at which the instruction begins — it is a name for the location, so it stands before anything the assembler emits. The mnemonic must precede its operands because the operation determines how many operands are expected and how they are interpreted: MVI takes a register and a byte, INR takes a register alone, NOP takes none. And the comment must come last because the delimiter that introduces it — a semicolon in Intel syntax — tells the assembler to ignore the rest of the line. Put a comment anywhere else and everything after it vanishes.
Only the mnemonic is compulsory, which is worth remembering because it explains why options beginning with a comment are wrong in principle as well as in practice: a line consisting of a comment alone is legal, but it is not an instruction, and the question asks about the fields of an instruction.
How the assembler uses the labels is the reason two passes are needed: a forward jump refers to a label defined later in the file, so the first pass builds a symbol table of label addresses and the second pass generates the machine code with those addresses filled in.
The value of labels is that they survive editing. Writing JMP LOOP instead of JMP 2050H means that inserting an instruction earlier in the program does not silently break the jump — the assembler recomputes the address.
Hence, the proper sequence is (i), (iv), (ii) & (iii).
Similar Questions
A microprocessor is a semiconductor chip fabricated with entire central processing unit (CPU) on it. It is a programmable device that accepts binary data from an input device, processes the data according to the instructions stored in the memory and provides results as output. Basically microprocessor performs two functions - (a) Fetches an instruction from the memory and (b) Performs the operation specified by the instruction. There are special inputs to the microprocessor called interrupts. External devices use these interrupts to get the microprocessor attention. A micro computer can be built by using 8085 microprocessor along with many other chips such as 8155, 8255, 8279, 8253, 8257, 8259, 8251 etc. 8085 microprocessor is 8-bit microprocessor which has 8-bit data registers where as 8086 is a 16-bit microprocessor.
The following 8051 assembly program is given. Answer the questions based on it.
Line No. Mnemonics 1 MOV SP, #4F H 2 SET B PSW.3 3 MOV R0, #25H 4 MOV R1, #0AH 5 MOV R2, #06H 6 PUSH 8 7 PUSH 9 8 PUSH 0AH . . . V V 20 POP 8 $D_7$ $D_6$ $D_5$ $D_4$ $D_3$ $D_2$ $D_1$ $D_0$ In 8255 programmable peripheral interface device, if the port A and port B are to be set in a hand shake mode along with port C, what are the bits in the 8 bit control word to be set as 0 1 0.
The number system for the machine code of the microprocessor 8085 is
Which of the options in a multipurpose instruction used to implement the interrupt of 8085 and serial data input ?
Both 8155 and 8255 programmable peripheral interface ICs have the following common features :
(i) Programmable I/Os
(ii) Either port A or Port B can be set as either input or output ports.
(iii) One 14-bit down counter
(iv) AD0 – AD7 are multiplexed address/datalines.The mnemonic of 8085 processor indicate :
List – I List – II a. RLC i. Rotate Accumulator Right through carry b. RRC ii. Rotate Accumulator Left through carry c. RAR iii. Rotate Accumulator Left d. RAL iv. Rotate Accumulator Right Codes :
Match the following :
List – I (Pin terminals) List – II (Applications) a. SID, SOD i. Wait state b. READY ii. Serial data transfer c. TRAP iii. Address Latch Control d. ALE iv. Interrupt Codes :
Assertion (A) : In serial communication system, when the transmission of data goes in both ways, it is called full-duplex system. Now if two micro processors are connected in full duplex mode, the amount of data transmitted will be double to the amount of data in half-duplex mode connection.
Reason (R) : When the transmission of data goes in one way, it is called half-duplex system and when the data moves in both ways, it is called full duplex system.
The assembler directive used to give name to some value or symbol for 8086 ASM-86 is
Important Questions from Microprocessors
An 8086 address bus is a/an _____ -bit bus
Program counter for any counter:
In the pin out configuration of the 8085 microprocessor, the sequential input data is represented by
Which of the following functions is not performed by a microprocessor?
Match the columns.
Pin
Description
a. D 0-D 7
1. Reset Input
b. RESET
2. Data Lines
c. A 0,A 1
3. Internal Address
