The number system for the machine code of the microprocessor 8085 is
Hexadecimal
Hexadecimal — option (D).
What the question is after. Machine code is the pattern of bits the processor actually executes. Nobody writes or reads those patterns as bits, though, and the number system in which 8085 machine code is expressed — in every manual, listing, monitor program and hex keypad of the era — is hexadecimal.
Why hexadecimal and not something else. The 8085 has an 8-bit data word, and 8 bits split exactly into two groups of four. Each group of four bits is one hex digit, so every byte is precisely two hex characters — no padding, no ambiguity:
| Binary | Hex | 8085 instruction |
|---|---|---|
| 0011 1110 | 3E | MVI A, data |
| 1100 0011 | C3 | JMP address |
| 0111 0110 | 76 | HLT |
The correspondence is not merely convenient, it is exact: \(16=2^{4}\), so converting between binary and hex is a digit-by-digit substitution needing no arithmetic at all. Addresses tell the same story — the 16-bit address bus gives a range of \(0000_{H}\) to \(FFFF_{H}\), four hex digits covering all 64 KB.
Why octal fails is worth seeing, because it was the earlier convention: 8 bits do not divide into groups of three, so a byte needs 2⅓ octal digits and the leading digit carries only two bits. Octal suits 12-, 24- and 36-bit machines; hexadecimal suits 8-, 16- and 32-bit ones, which is why it displaced octal as byte-oriented processors took over.
The point of care. Strictly, the machine code is binary — that is what sits in memory and drives the instruction decoder. Hexadecimal is a human-readable representation of it. Examination questions of this form ask for the number system in which 8085 machine code is written and handled, and the expected answer is hexadecimal; the official key records (D).
BCD, for completeness, is not a machine-code notation at all. It encodes one decimal digit per nibble and exists for arithmetic on decimal quantities — which is why the 8085 provides DAA, the decimal adjust accumulator instruction, to correct a binary addition back into BCD form.
Hence, the answer is Hexadecimal.
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.
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.Each instruction in an assembly program has the following fields :
(i) Lable field
(ii) Operand field
(iii) Comment field
(iv) Mnemonic fieldPlease write the proper sequence of fields :
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
