+.387
+ PUBLIC MXSTARTLINE
+ EXTRN MX_BYTESPERLINE:BYTE
+MX_TEXT SEGMENT PARA PUBLIC USE16 'CODE'
+ ASSUME CS:MX_TEXT, DS:DGROUP, SS:DGROUP
+MXSTARTLINE:
+ push bp
+ mov bp,sp
+ sub sp,0
+ mov ax,word ptr 6[bp]
+ mul word ptr cs:MX_BYTESPERLINE
+ xchg ax,bx
+ mov dx,3daH
+L$1:
+ in al,dx
+ test al,8
+ jne L$1
+ mov dx,3d4H
+ mov al,0cH
+ mov ah,bh
+ cli
+ out dx,ax
+ mov al,0dH
+ mov ah,bl
+ out dx,ax
+ sti
+ mov dx,3daH
+L$2:
+ in al,dx
+ test al,8
+ je L$2
+ xor ax,ax
+ mov sp,bp
+ pop bp
+ retf 2
+MX_TEXT ENDS
+ END