Uncover the Iconic Sound of Super Mario Bros. 3!

Uncover the Iconic Sound of Super Mario Bros. 3!

Table of Contents

1. Introduction
2. The Sound Effect Queues in Super Mario Bros. 3
   • Queue 1: Sound effects using the first square Wave Channel
   • Queue 2: Sound effects using the Second square wave channel
   • Queue 3: Sound effects using the noise or triangle wave channels
3. Sound Effect Management in Super Mario Bros. 3
   • Two-byte system for managing sound effects
   • Bit-wise prioritization of sound effects
   • Overwriting of sounds when multiple triggered in one frame
4. The Problematic Second Sound Effect Queue
   • The combination of bit-assigned and byte-assigned sound effects
   • Flaw 1: Incomplete assignment of sound effects in the queue
   • Flaw 2: Contradictory prioritization of the 1up sound effect
   • Flaw 3: Assembly code oversight leading to the glitched 1up sound
5. Understanding the Corrupted 1up Sound Effect
   • The relationship between tail wagging and 1up sounds
   • The role of the length parameter in the glitch
6. The Complexity of Sound Effect Programming
7. Conclusion

The Sound Effect Queues in Super Mario Bros. 3

In the world of retro gaming, Super Mario Bros. 3 holds a special place. Not only is it renowned for its gameplay and visuals, but it also offers a fascinating glimpse into the complexities of sound effect programming. To understand one particularly interesting glitch, we need to examine how the game organizes and manages its sound effects queues.

Queue 1: Sound effects using the first square wave channel

The first queue in Super Mario Bros. 3 is dedicated to sound effects that utilize the first square wave channel. This category includes sounds like jumping, bumping, swimming, kicking, pipe entering, fireball shooting, p-meter sound, and frog suit hopping. These sound effects are assigned to specific bits within a byte, creating a prioritization system Based on their significance.

Queue 2: Sound effects using the second square wave channel

The second queue is responsible for sound effects that utilize the second square wave channel. Examples of these sound effects include coin collection, power-up reveal, vine reveal, cannon boom, text beep, power-up sound, 1up sound, poof sound, unused sound, losing Kuribo's shoe sound, and tail wagging sound. However, this queue introduces a complication by assigning some sound effects to bits and others to entire bytes, leading to unintended side effects.

Queue 3: Sound effects using the noise or triangle wave channels

The third queue in Super Mario Bros. 3 handles sound effects that utilize the noise or triangle wave channels. This category includes sounds like breaking bricks, firing cannons, throwing boomerangs, airship flight, hammer bro marching, and Mario skidding. Similar to the previous queues, these sound effects are managed using specific bits and bytes within a byte.

Sound Effect Management in Super Mario Bros. 3

To understand the glitch that causes the extended version of the 1up sound, we must Delve into the sound effect management system implemented in Super Mario Bros. 3. The game uses a two-byte system to control the initiation and continuation of sound effects, ensuring smooth playback.

Each sound effect in the queues is represented by a single bit, which is set when the sound should be played. When more than one sound is triggered in a single frame, multiple bits are set. The sound effects are then prioritized based on their assigned bits' significance, with lesser significant bits taking precedence over higher significant bits.

Once a sound needs to be played, the entire byte associated with the queue is examined, starting from the least significant bit. The corresponding sound effect is initialized, and the byte is copied to a second byte to keep track of the currently playing sound. However, the glitch arises when two sound effects, one assigned to a bit and another to a byte, are triggered simultaneously.

In such cases, where both bit-wise and byte-wise assigned sound effects are queued together, the byte-wise sound effects overwrite the bit-wise sound effects. This undermines the intended priority system and leads to unexpected behavior.

The Problematic Second Sound Effect Queue

The second sound effect queue in Super Mario Bros. 3 presents several flaws that contribute to the glitched extended version of the 1up sound. These flaws involve the incomplete assignment of sound effects, contradictory prioritization of the 1up sound, and an oversight in the assembly code.

Flaw 1: Incomplete assignment of sound effects in the queue

The second sound effect queue suffers from the incomplete assignment of sound effects. While the majority of sound effects in this queue are assigned to bits, four specific sound effects (poof, unused, Kuribo's shoe, and tail wagging) are assigned to entire bytes. This combined system leads to unintended side effects when sound effects with different assignment methods are queued together.

Flaw 2: Contradictory prioritization of the 1up sound effect

The prioritization of sound effects in Super Mario Bros. 3 contradicts itself when it comes to the 1up sound effect. Despite being assigned to a lower priority bit (bit 6), the game's designers introduced a specific case to prioritize the 1up sound over every other sound effect. This special treatment for the 1up sound disrupts the intended priority system and causes further complications.

Flaw 3: Assembly code oversight leading to the glitched 1up sound

The glitched extended version of the 1up sound arises from an oversight in the assembly code handling the second sound effect queue. The code mistakenly uses the "STY" instruction instead of "STA," leading to the incorrect storage of values that allow sound effects to Continue playing. This oversight prevents the prevention of sound conflicts and ultimately results in the glitched 1up sound.

Understanding the Corrupted 1up Sound Effect

To understand why the tail wagging sound produces such a long corrupted 1up sound, we need to consider the relationship between these two sound effects and the unique format used for byte-assigned sound effects.

The tail wagging sound effect is relatively short in its original form. However, the glitched 1up sound occurs because the corruption transfers the length parameter from the tail wagging sound to the 1up sound due to the offset-based storage for these byte-assigned sound effects. This offset can be larger, resulting in a longer duration for the glitched 1up sound.

The glitched 1up sound is a combination of the corrupted tail wagging sound alongside the end portion of the powering up sound effect. Both sound effects are stored next to each other in the game's ROM, even though they produce distinct notes. This shared data and the mishandling of lengths contribute to the unique sound produced by the glitched 1up effect.

Conclusion

The glitched extended version of the 1up sound in Super Mario Bros. 3 showcases the intricacies and complexities of sound effect programming in retro games. The combination of bit-assigned and byte-assigned sound effects, contradictory prioritization, and oversight in the assembly code all contribute to this fascinating glitch. Understanding the inner workings of sound effect queues and their management sheds light on the technical challenges faced by game developers and the unexpected consequences that can arise.