8085 program to access and exchange the content of Flag register with register B

MicrocontrollerMicroprocessor8085

In this program we will see how to exchange the content of Flat register with register B.

Problem Statement

Write 8085 Assembly language program to swap the content of flag register and the register B.

Discussion

As we cannot access the flag register content directly, we have to take the help of stack. By using stack, we can push the content of PSW (Accumulator and Flag). Then we can get it back and store into some other registers. Similarly, from other register, we have to push them into stack, then pop it to PSW.

Here if we want to exchange the value of B and F, then at first we have to make a copy of B to C. When we will push the PSW into stack, then pop to BC, the Acc content will be loaded to B, and Flag register content will be loaded to C.

Input

Here we are not providing any additional inputs. We are directly storing a value to B, then swapping it to flag register. In the program the B is containing 45H, after executing the program, 45H will be loaded to Flag register.

Flow Diagram

Program

Address
HEX Codes
Mnemonics
Comments
F000
31, 00, 90
LXI SP,9000
Initialize stack pointer
F003
06, 45
MVI B,45H
Load B with 45H
F005
48
MOV C,B
Save B into C
F006
F5
PUSH PSW
Store AF into stack
F007
C5
PUSH B
Store BC into stack
F008
F1
POP PSW
Pop and store to AF
F009
C1
POP B
Pop and store to BC
F00A
41
MOV B, C
Move C to B
F00B
76
HLT
Terminate the program


Output

Flag register will be loaded with 45H.

raja
Published on 22-Jan-2019 15:34:43
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