ORG 100H ; ADD +100H TO ALL ADDRESSES (REQUIRED FOR .COM FILE).
MOV AX, 0013H
INT 10H ; set video mode with AH and AL
MOV AX, 0C03H
XOR DX, DX
MOV CX, 0310D
MOV BX, CX
DRAW: PUSH CX
MOV CX, BX
MOV AH, 07H
INT 21H
CMP AL, 73H
JZ S
CMP AL, 61H
JZ A
CMP AL, 77H
JZ W
CMP AL, 64H
JZ D
V: MOV AL, 03
MOV AH, 0CH
INT 10H
POP CX
LOOP DRAW
MOV AH, 07H
INT 21H
RET
S: INC DX
JMP V
A: DEC CX
MOV BX, CX
JMP V
W:
DEC DX
CMP DX, 0
JZ AAAA
JMP V
D:
INC CX
MOV BX, CX
JMP V
AAAA: XOR DX, DX
JMP V