9] Design and devlop an assembly program to display messages ‘FIRE’ and ‘HELP’ alternately with flickering effects on a 7-segment display interface for a suitable period of time. Ensure a flashing rate that makes it easy to read both the messages( Examiner does not specify these delay values nor is it necessary for the student to compute these values).
9] Program code (lab9.asm)
.model small
.stack 64
.data
pa equ 0e880h
pb equ 0e881h
pc equ 0e882h
ctrl equ 0e883h
fire db 71h,11h,0ah,61h
help db 91h,61h,0e3h,31h
msg db 'press any key on kbd to return to dos','$'
.code
mov ax,@data
mov ds,ax
mov al,90h
mov dx,ctrl
out dx,al
mov ah,09h
lea dx,msg
int 21h
again:lea bp,fire
call disp
call delay
lea bp,help
call disp
call delay
mov ah,6h
mov dl,0ffh
int 21h
jz again
mov ah,4ch
int 21h
delay proc
mov ax,08fffh
agn1:mov cx,05fffh
agn:loop agn
dec ax
jnz agn1
ret
delay endp
disp proc
mov si,3
nxtchr:mov ah,8
mov al,ds:[bp+si]
nxtseg:mov dx,pb
out dx,al
mov ch,al
mov al,0
mov dx,pc
out dx,al
mov al,0f0h
out dx,al
dec ah
jz below
mov al,ch
ror al,1
jmp nxtseg
below: dec si
cmp si,-1
jne nxtchr
ret
disp endp
end
