Questions & Answers of 8085 Microprocessor Basics, Architecture, Programming and Interfacing

Question No. 62

An output device is interfaced with 8-bit microprocessor 8085A. The interfacing circuit is shown in figure

The interfacing circuit makes use of 3 Line to 8 Line decoder having 3 enable lines E1 , E¯2 , E¯3 . The address of the device is

Question No. 162

In an 8085 microprocessor, the following program is executed

Address location – Instruction

2000H XRA  A
2001H MVI B,04H
2003H MVI A, 03H
2005H RAR
2006H DCR B
2007H JNZ 2005

At the end of program, register A contains

Question No. 233

In 8085A microprocessor, the operation performed by the instruction LHLD 2100H is

Question No. 34

A portion of the main program to call a subroutine SUB in an 8085 environment is given below.
It is desired that control be returned to LP+DISP+3 when the RET instruction is executed in the subroutine. The set of instructions that precede the RET instruction in the subroutine are

Question No. 47

When a "CALL Addr" instruction is executed, the CPU carries out the following sequential operations internally:

Note: (R) means content of register R
((R)) means content of memory location pointed to by R
PC means Program Counter
SP means Stack Pointer

Question No. 25

In an 8085 microprocessor, the contents of the Accumulator, after the following instructions are executed will become


Question No. 10

An input device is interfaced with Intel 8085A microprocessor as memory mapped I/O. The address of the device is 2500H. In order to input data from the device to accumulator, the sequence of instructions will be

Question No. 45

The contents (in Hexadecimal) of some of the memory locations in an 8085A based system are given below:

Address Contents
.. ..
26FE 00
26FE 01
2700 02
2701 03
2702 04
.. ..
The contents of stack (SP), program counter (PC) and (H,L) are 2700 H, 2100 H and 0000 H respectively. When the following sequence of instructions are executed.
2100 H:        DAD SP
2101 H:        PCHL
the content of (SP) and (PC) at the end of execution will be