User Files for Super Mario World

What Is This?

Crash Using Yoshification

Open bus & Payload

• The CPU reads two bytes from $01f0cb + (mouth routine pointer * 2) and jumps to that location in bank 01. This time, the mouth routine pointer is 6, so it jumps to $01221d in the open bus.
• The value of mdr is 01 derived from the bank, so ora($01,x) is executed.
  • x == 8 (Yoshi's slot number)
  • $09 == 01(high byte of player y position, next frame...$97)
  • $0a == 1c(x position of lowest slot, lowbyte + 2)
• Therefore, ora($01,x) = ora $011c01 = ora #$10
• Consequently, the next MDR value becomes 10, and bpl $10 is executed. This likely allows jumping over various registers until the CPU reaches $01421d.

8e c6 13 64 10 cb 80 f8
//stx$13c6  stz$10  wai  bra  $4218
e9 04 8d 00 01 60 80 f8
//sbc#$04  sta$0100  rts  bra  $4218

$01421d   wai
(Interrupts by IRQ)
$01421e   bra $4218
$014218   stx $13c6          //x == 8
$01421b   stz $10
$01421d   wai
(interrrupts by NMI, below is the 2nd frame)
$01421e   bra $4218
$014218   sbc #$04          //a == 1d - 04 - carry (==18)
$01421a   sta   $0100
$01421d   rts

Flow Leading Up To The Crash

1. First, to spawn Yoshi in slot 8, take the shell in slot 9 and hit the block containing Yoshi while wedging it into the block on the left($13 parity must be considered). This allows Yoshi to spawn before the message box fills slot 8.
2. Kick the shell from slot 9 and take damage at the right spot. Adjust carefully to face left while moving right by inertia, step on the shell to spawn the naked koopa in slot 6, and scroll left at the right moment. This causes 3f? freeze, allowing you to place the naked koopa where you want. (Be careful not to break $13 parity)
3. Throw the shell in slot 0 to the left, setting the x-coordinate to 0x1a one frame? before the crash. (Adjustment for $0a)
4. Yoshification succeeds without needing to pause when both the shell's and naked koopa's slot numbers are even? and $13 is even at the frame the shell spawns.

Is Further Improvement Possible?

What To Yoshify

1. shell
2. naked koopa (would require a pause if you could because of the initialization of the naked koopa)

Where To Do

How To Despawn Yoshi

1. hole on the left end of the level
2. use corner clip
3. use message box to get through the floor (didn't work)
4. use null sprite overload

Other Possibilities

1. YI2: N/A
2. YI3: N/A
3. YI4: No improvements here, just used the same technique of shell jumping to reduce lag
4. Iggy: Using 6/5 trick to keep speed in the first section. Included more entertainment and not collected flower in second room.

• 1-1: 370 - 368 - 368
• 1-2: 347 - 345 - 346
• 4-1: 340 - 339 - 340
• 4-2: 356 - 344 - 354 (time units very misleading versus real-time due to beanstalk)
• 8-1: 200 - 197 - 199
• 8-2: 338 - 337 - 340
• 8-3: 244 - 242 - 242 (intentionally slows down to avoid fireworks)
• 8-4: 317 - 309 - 306

• 1-1: Crashes into pipe in underground.
• 1-2: Goes over the ceiling instead of through the wall.
• 4-1: Misses many coins, slows down near the end.
• 4-2: Goes between the bricks instead of through the wall, which further requires beanstalk manipulation instead of being able to enter pipe directly.
• 8-1: Slows down in the middle for no good reason, misses enemies.
• 8-2: Slow start. Then big jump followed by Piranha collision glitch could be done faster. In fact I did do it faster and had a better looking glitch, however, right afterwords I stupidly pressed load instead of save, and didn't redo the effort into getting that part to be optimal in entertainment and time.
• 8-3: Didn't kill enough Hammer Brothers.
• 8-4: Didn't wall jump into pipe, swimming suboptimal.