Super Mario Bros. - Spiny Egg Intended Behavior

[ColecoFan1981]

Has anyone here been aware that the Spiny Egg movement in the NES version of Super Mario Brothers is not as intended? The link below will tell.

Link about this:
https://tcrf.net/Talk:Super_Mario_Br...ontal_Movement

What we got:

DifLoop:  lda PRDiffAdjustData,y
          sta $01,x
          iny
          iny
          iny
          iny
          dex
          bpl DifLoop
          ldx ObjectOffset
          jsr PlayerLakituDiff
          ldy Player_X_Speed
          cpy #$08
          bcs SetSpSpd
          tay
          lda PseudoRandomBitReg+1,x
          and #$03
          beq UsePosv
          tya
          eor #$ff
          tay
          iny
UsePosv:  tya
SetSpSpd: jsr SmallBBox
          ldy #$02
          sta Enemy_X_Speed,x
          cmp #$00
          bmi SpinyRte
          dey

What should have been:

SetSpSpd: ldy #$02
          sta Enemy_X_Speed,x
          cmp #$00
          bmi SpinyRte
          dey
SpinyRte: jsr SmallBBox

Move the jsr instruction to below the dey instruction, and the movement will be as intended.

This same fix can also be applied to these other SMB variations:
Super Mario Bros. (FDS)
Super Mario Bros. 2 (Japan) (FDS)
All-Night Nippon Super Mario Bros. (FDS)
Vs. Super Mario Bros.
(Please note the offsets for the SetSpSpd instruction will be different for these versions than the NES cartridge version, which is at offset 0x4444 when using a hex editing program like Hexecute or Hex Workshop.)

~Ben

[JohnnyA]

I would be very interested to see a before and after video of the behavior, as it's hard for me to picture how the behavior would change from just the description. Neat nonetheless.

[Graham Mitchell]

I would be very interested to see a before and after video of the behavior, as it's hard for me to picture how the behavior would change from just the description. Neat nonetheless.

It sounds like they're supposed to bounce before turning into a spiny. Pretty interesting!

The page also talks about an alternate ground theme music that Koji Kondo has alluded to in interviews. I'd like to hear that as well.

[ColecoFan1981]

Here's an "after" video:
https://www.youtube.com/watch?v=b-jwlt24NLo

~Ben

[Tanooki]

I wondered what this was all about as code means nothing to me. That would have made the game quite a bit harder than probably even necessary so I can see why they left it out. I'm more surprised as downright ugly as the FDS SMB2 was they didn't include it in there.

[drunk3nj3sus]

I wondered what this was all about as code means nothing to me. That would have made the game quite a bit harder than probably even necessary so I can see why they left it out. I'm more surprised as downright ugly as the FDS SMB2 was they didn't include it in there.

It's been awhile since I've played it but I have SMB2j on my wii and I'm pretty sure the spiney behavior is different in it

[Graham Mitchell]

Wow, looks like it would've been more challenging. I'd like to patch it into vs smb and try it.

[ColecoFan1981]

On the side, here's a recently uncovered SMB glitch: you have to beat the game the first time around. When the secondary hard mode is activated, start a 2 player game.

Go to World 5-2 (provided both Mario and Luigi have enough lives) and be Small on the vine and wait for the Hammer Brother to throw a Hammer at you while on the vine. When it is the next player's turn, the next player should be at 1-2, 2-2 or 4-2 and a vine will grow from the ground. In 1-2, this vine allows you to rack up infinite lives from a Buzzy Beetle.

https://www.youtube.com/watch?v=RDEhCty45Sk

~Ben