This is a very simple program that uses text mode to display a boucing "ball." The ball is just a character that moves across the screen, erasing all in its path. It is coded to work like a screensaver, so the program ends when any key is hit.
NOTE: I am in no ways an assembly guru, if anything i'm a noob; however, if this code helps someone out, then thats great.
This could be good framework for coding in graphics mode. Just replace the ball character with a bit pattern. Anyways, enjoi.
page 60,132
;--------------------------------------------------------------------------
; Name: Nathan Gallagher
; Description: Creates a character (ball) that moves accross the screen, acts as a screensaver
; will end when a key is pressed
;--------------------------------------------------------------------------
;-----------------------------------------------------------------------
;stack segment
sseg segment para stack 'stack'
db 120 dup(?) ;reserve 120 bytes for the stack
sseg ends
;-----------------------------------------------------------------------
;constants
;-----------------------------------------------------------------------
;data segment
dseg segment para 'data'
ball db 'O' ;create ball character
x db 01h ;create the x-coordinate variable
y db 01h ;create the y-coordinate variable
incX db 01h ;create the variable that moves x
incY db 01h ;create the cariable that moves y
eraser db ' ' ;create an erasor to clear the ball character
dseg ends
;----------------------------------------------------------------------
;code segment
cseg segment para 'code'
main proc far ;this is the program entry point
assume cs:cseg, ds:dseg, ss:sseg
mov ax,dseg ;load the data segment value
mov ds,ax ;assign value to ds
call cursor ;Set up initial cursor
;this runs until user hits the keyboard
start: mov dl,incX
add dl,x
mov x,dl ;increment X
mov dl,incY
add dl,y
mov y,dl ;increment Y
call cursor ;set up our cursor
;see if we need to swap anything
call swapX ;swap our X inc value if needed
call swapY ;swap our Y inc value if needed
;time to draw our ball!
mov dl,ball
mov ah,2h
int 21h ;output the ball
;delay
call wait
;erase ball
call cursor
mov dl,eraser ;erase the ball
mov ah,2h
int 21h
keyboard: mov ah,1 ;loop at end to display results
int 16H
jnz quit ;if a key is pressed, hit the bricks!
jmp start ;jump to start if key isnt hit
quit: call cls ;clear screen before returning to DOS
mov ah,4Ch ;set up interupt
int 21h ;Interupt to return to DOS
main endp
;----------------------------------------------
; Delay process
;runs through multiple loops to make the wait more potent
;----------------------------------------------
wait proc
mov cx,12000d
delay1: in al,61h
and al,10h
cmp al,ah
je wait
mov ah,al
loop delay1
mov cx,12000d
delay2: in al,61h
and al,10h
cmp al,ah
je wait
mov ah,al
loop delay2
mov cx,12000d
delay3: in al,61h
and al,10h
cmp al,ah
je wait
mov ah,al
loop delay3
mov cx,12000d
delay4: in al,61h
and al,10h
cmp al,ah
je wait
mov ah,al
loop delay4
mov cx,12000d
delay5: in al,61h
and al,10h
cmp al,ah
je wait
mov ah,al
loop delay5
ret
wait endp
;----------------------------------------------
;----------------------------------------------------------------------
;here's a procedure that sets the cursor
;----------------------------------------------------------------------
cursor proc
mov ah,02 ;load sub function for int
mov bh,00 ;sets page 0
mov dl,x ;sets the column based on x
mov dh,y ;sets the row based on y
int 10h ;calls interupt
ret
cursor endp
;----------------------------------------------------------------------
;Loops for changing incX and incY ------------------------------------------------------------------
swapX proc
cmp x,79d
jge goLeft ;if x is at the limit, jump
cmp x,0d
jle goRight ;if x is at the limit, jump
jmp Xbottom
goLeft: mov incX,-1 ;make the ball go left
jmp Xbottom
goRight: mov incX,1 ;make the ball go right
jmp Xbottom
Xbottom: nop
ret
swapX endp
;---------------------------------------------------------------------------
swapY proc
cmp y,25d ;if y is at the limit, jump
jge goUp
cmp y,0d
jle goDown ;if y is at the limit, jump
jmp yBottom
goUp: mov incY,-1 ;make the ball go up
jmp yBottom
goDown: mov incY,1 ;make the ballgo down
jmp yBottom
yBottom: nop
ret
swapY endp
;---------------------------------------------------------------------------
;----------------------------------------------------------------------
; Here is a procedure that clears the screen
;----------------------------------------------------------------------
cls proc
mov ax,0600h ;scroll screen
mov bh,07 ;normal attribute
mov cx,0000 ;start at 00,00
mov dx,184fh ;end at 24,79
int 10h ;call int 10
ret
cls endp
;---------------------------------------------------------------------
cseg ends
end main ;Program exit pointWe're a friendly, industry-focused community of developers, IT pros, digital marketers, and technology enthusiasts meeting, networking, learning, and sharing knowledge.