Notes

.model tiny
.data
pos db 80 DUP(00h)
len db 80 DUP(00h)
seed dw 734, 660, 210, 581, 128, 202, 549, 564, 459, 961, 585, 882, 277, 614, 981, 806, 576, 137, 886, 99
dw 911, 92, 385, 795, 278, 913, 357, 259, 946, 793, 638, 635, 922, 768, 192, 417, 561, 134, 153, 787
dw 857, 89, 632, 74, 270, 142, 928, 135, 724, 414, 539, 421, 157, 589, 229, 238, 507, 246, 430, 610
dw 526, 425, 75, 186, 571, 687, 995, 922, 850, 709, 265, 780, 946, 395, 930, 426, 403, 593, 620, 995
dw 199, 983, 344, 631, 326, 882, 198, 790, 692, 671, 180, 882, 609, 56, 779, 269, 814


.code
org 0100h

main proc
mov ah, 00h
mov al, 03h
int 10h

mainLoop:

mov ax, 0B800h
mov es, ax

call randPos

mov cx, 0FFFFh
call delay

call randLen

mov cx, 80
tail:
call checkTail
loop tail

mov cx, 80
body:
call checkBody
loop body

mov cx, 80
neck:
call checkNeck
loop neck

mov cx, 80
head:
call checkHead
loop head

mov cx, 0FFFFh
call delay
call scrollDown
mov ah, 0Bh
int 21h
cmp al, 00h
je mainLoop
main endp


checkBody proc
mov bx, cx
dec bx
cmp pos[bx], 3
jne chkB
mov al, len[bx]
dec al
mov len[bx], al
add bx, bx
mov DI, bx
mov ah,0Ah
call print
chkB:
ret
checkBody endp
checkHead proc
mov bx, cx
dec bx
cmp pos[bx], 1
jne chkH
mov pos[bx], 2
add bx, bx
mov DI, bx
mov ah,0Fh
call print
chkH:
ret
checkHead endp
checkNeck proc
mov bx, cx
dec bx
cmp pos[bx], 2
jne chkN
mov pos[bx], 3
add bx, bx
mov DI, bx
mov ah,07h
call print
chkN:
ret
checkNeck endp
checkTail proc
mov bx, cx
dec bx
cmp len[bx], 3
ja chkT
cmp len[bx], 0
je chkT
mov pos[bx], 0
mov al, len[bx]
dec al
mov len[bx], al
add bx, bx
mov DI, bx
mov ah,02h
call print
chkT:
ret
checkTail endp
delay proc
dlay:
nop
loop dlay

ret
delay endp
print proc
push cx
mov cx, 30
call delay
call randChar
stosw
pop cx
ret
print endp
randChar proc

push bx
push ax
mov ah,2ch
int 21h

mov ax,dx
add dx,seed[bx]
pop bx
add dx,bx
push bx
mov ax,dx
mov bx, 94
mov dx, 0
div bx
pop ax
mov al, dl
add al, 33
pop bx
ret
randChar endp
randLen proc
push bx
mov ah,2ch
int 21h
mov ax, dx
mov dx, 0
mov bx, 97
div bx
mov bx, dx
add dx, seed[bx]

mov ax,dx
mov bx, 6
mov dx, 0
div bx
add dx, 7
pop bx
mov len[bx],dl

ret
randLen endp
randPos proc
rerand:
push cx
mov ah,2ch
int 21h
pop cx
mov ax, dx
mov dx, 0
mov bx, 97
div bx
mov bx, dx
add dx,seed[bx]
mov ax,dx
mov bx,80
mov dx, 0
div bx
mov bx, dx
checkCollosion:
mov dl, len[bx]
cmp dl, 0
je Create
inc bx
cmp bx, 80
ja rerand
jmp checkCollosion
Create:
mov pos[bx],1

ret
randPos endp
scrollDown proc
push cx
mov ah,07h
mov al,1
mov cl,0
mov ch,0
mov dh,80
mov dl,80
mov bh,0
int 10h
pop cx
ret
scrollDown endp
.exit
end main