The document describes an experiment using an 8255 chip to blink LEDs connected to port A with a delay. The flow chart shows the program flow which initializes the I/O ports as outputs, writes 00H to port A, calls a delay subroutine, writes FFH to port A, calls the delay subroutine again, and loops continuously toggling the LEDs. The assembly language listing provides the code to initialize the I/O addresses, toggle the LEDs on port A, and implement a delay subroutine using a decrementing counter.

1. Experiment No. 8
LED Blinking using 8255

3. Statement:
1. I/O addresses of PA, PB, PC & CWR are set to 80H-83H
respectively. Each port is interfaced with eight LEDs. Write an
ALP to toggle LEDs connected to PORTA with some delay
continuously.

4. Flow Chart Start
Get I/O Mode format to make all ports as
output into Acc.
Get 00H into A and Send it to PA
Call Delay
Send to CWR
Get FFH into A and Send it to PA
Call Delay

5. Address Label Instruction
7100,1,2 DELAY: LXI D,0FFFH
3 DCX D
4 MOV A,D
5 ORA E
6,7,8 JNZ UP
9 RET
Address Label Instruction
6900, 1 MVI A,80H
2,3 OUT CWR
4,5 MVI A,00H
6,7 OUT PA
8,9,A CALL DELAY
B,C MVI A,FFH
D,E OUT PA
F,10,11 CALL DELAY
12,13,14 JMP UP1
15 RST1
UP:
UP1: