Software
Program
The program, written in Assembly Language, is a menu (interactive) driven program, executed on the computer, which allows the user to choose between three (3) appliances, to turn them on/off. The user has the option to be in this program or use his/her computer for other application programs at the same time i.e. the application program (s) can be running in the background while the user turns on/off an appliance (s) or the program can be running in the background whilst the user is using word processor or excel etc.
The user chooses an appliance at a time by pressing a specific key. One key is used to turn the appliance both on and off. When the key is pressed a sub-program tests for a key press. Once a key has been pressed, the program now compares the specific key pressed to the key options for the menu. If an option key is pressed, the signal is then transferred to the extended parallel port of the computer. After this, the menu screen is displayed again, so that the user can further turn on/off more appliances or the same appliance.
However, it is advised to give a delay time between options, so that signals would not be corrupted and may lead to the toggling of appliances on/off.
See Figure 3 - Flow Chart for the Menu Driven Program.
See the Assembly Language Menu Driven Program attached.
Figure 3 - Flow Chart for Menu Driven Program
Assembly Language Menu Driven Program
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TITLE Program.asm
;This program is used to controll the multiplexer in the Power Line Appliance Controller
sseg SEGMENT STACK ;establish a stack segment
DW 256 DUP (?) ;this will create a 256 word stack
sseg ENDS
dseg SEGMENT ;establish data segment
menu db "Power Line Appliance Controller",0Ah,0Dh,"$"
menu1 db "Press 1 --> Fan on<>off",0Ah,0Dh,"$"
menu2 db "Press 2 --> CD Player on<>off",0Ah,0Dh,"$"
menu3 db "Press 3 --> Kitchen Lights on<>off",0Ah,0Dh,"$"
menu4 db "Press Esc --> Exit from this menu",0Ah,0Dh,"$"
messfan db "Fan",0Ah,0Dh,"$"
messcd db "CD Player",0Ah,0Dh,"$"
messlights db "Kitchen Lights",0Ah,0Dh,"$"
message1 db "No Key Pressed",0Ah,0Dh, "$"
dseg ENDS
cseg SEGMENT
ASSUME ss:sseg,ds:dseg,cs:cseg
start: mov ax,dseg ;initialize data segment
mov ds,ax
top: call clrscn ;clears the screen
lea dx, menu ;the following lines of code
call display ;displays the
lea dx, menu1 ;lines of the menu
call display
lea dx, menu2
call display
lea dx, menu3
call display
lea dx, menu4
call display
delay1: call delay
call if_key ;checks to see if a key was pressed
mov bl, al ;save a copy of the key pressed
mov al, bl ;retrieves the copy of key pressed
cmp al, 31h ;test to see if key pressed was 1
je fan ;if key was 1 go to fan
mov al, bl ;retrieves the copy of key pressed
cmp al, 32h ;test to see if key pressed was 2
je cd ;if key was 2 go to cd
mov al, bl ;retrieves the copy of key pressed
cmp al, 33h ;test to see if key pressed was 3
je lights ;if key was 3 go to lights
mov al, bl ;retrieves the copy of key pressed
cmp al, 1bh ;test to see if key pressed was Esc
je exit ;if key was Esc go to exit
mov al, bl
cmp al, 0h ;if al=0, no key was pressed
jmp top
fan: lea dx, messfan
call display ;sends out a message to say that the fan was selected
mov al, 1h ;sets pins A=0, B=1, G'=lo
call out ;sends 01 out via the parallel port
call delay ;gives a small delay
mov al, 0h
call out
call delay
jmp top
cd: lea dx, messcd
call display ;sends out a message to say that the CD Player was selected
mov al, 2h ;sets pins A=1, B=0, G'=lo
call out ;sends 10 out via the parallel port
call delay ;gives a small delay
mov al, 0h
call out
call delay
jmp top
lights: lea dx, messlights
call display ;sends out a message to say that the Kitchen Lights were selected
mov al, 3h ;sets pins A=1, B=1, G'=lo
call out ;sends 11 out via the parallel port
call delay
mov al, 0h
call out
call delay
jmp top
exit: mov ax,4c00h ;return to DOS! (bye-bye)
int 21h
;clears the screen
clrscn proc
mov ax, 02h ;option 2 for bios int 10
int 10h
ret
clrscn end
;display a string to screen
display proc ;dx holds beginning offset of string
mov ah, 09h ;option 9 of bios service int 21
int 21h ;invoke int 21
ret
display endp
;tests to see if a key was pressed
if_key proc
mov ah, 01h
int 16h
jz no_char
mov ah, 0h
int 16h
ret
no_char: mov ax, 0h
ret
if_key endp
;gives a three seconds delay
delay proc
mov ah, 86h ;function for delay
mov cx, 002dh ;delay for 3 seconds or 3000000us
mov dx, 0c6c0h
int 15h ;invoke int 15
ret
delay endp
out proc
mov dx, 378h
out dx, al
out endp
cseg ENDS
END start
