# The Concealed Weakness in SNES Hardware: How Inexpensive APU Resonators Impact Performance
## Introduction
The Super Nintendo Entertainment System (SNES) is frequently viewed as one of the most dependable gaming consoles ever produced. Yet, recent investigations by the TASBot community have uncovered an unexpected flaw in its hardware: the employment of low-cost ceramic resonators in the Audio Processing Unit (APU). These components, anticipated to deliver a consistent clock rate, have instead caused discrepancies that influence gameplay accuracy, especially for speedrunners and tool-assisted speedruns (TAS).
## The Function of the APU in SNES Performance
The SNES APU is tasked with audio processing and synchronization with the console’s CPU. According to Nintendo’s official documents, the APU is designed to operate at a fixed frequency of **24,576 Hz**, with the corresponding Digital Signal Processor (DSP) sample rate at **32,000 Hz**. Ideally, this should guarantee that all SNES units perform uniformly under identical conditions.
However, TASBot researchers have found that the actual clock rate of the APU can fluctuate marginally due to elements such as **temperature, system age, and slight physical differences** in the ceramic resonators utilized in the hardware. This fluctuation results in minor yet notable discrepancies in how games perform on various SNES systems.
## The Effect on Speedrunning and TASBot
For casual gamers, the APU timing problem might merely lead to **slightly modified in-game music pitch**. However, for speedrunners and TASBot operators, these irregularities pose significant hurdles.
TASBot, a robotic system crafted to execute frame-perfect inputs on authentic hardware, depends on **accurate timing** to flawlessly reproduce tool-assisted speedruns (TAS). Nevertheless, due to the **unreliable clock speed of the SNES APU**, TASBot often faces **desynchronization challenges**, leading to failed inputs or unforeseen outcomes.
Allan “dwangoAC” Cecil, a prominent TASBot researcher, asserts that the issue is **”constant, pervasive, and unavoidable.”** The unpredictable fluctuations in APU timing imply that even if a speedrun functions seamlessly in an emulator, it may not perform identically on a genuine SNES console.
## Exploring the APU Clock Variability
To gain better insight into the scope of the problem, Cecil executed an **informal online survey** where SNES owners were asked to gauge their console’s DSP clock speed. The findings were enlightening:
– The **average DSP clock speed** noted was **32,078 Hz**, considerably higher than Nintendo’s official specification of **32,000 Hz**.
– The **slowest and fastest DSPs** recorded during the survey displayed a **234 Hz difference**, or roughly **0.7% variation**.
– Temperature shifts had a **minimal effect**, yielding only an **8 Hz increase** on average between cold and warm consoles.
These results indicate that **SNES APUs may be gaining speed over time**, likely due to the deterioration of the ceramic resonators.
## Why Ceramic Resonators Are the Dilemma
In contrast to **quartz crystal oscillators**, which are widely employed in electronics for their **high precision and stability**, ceramic resonators are **more economical but less dependable**. Over time, they are known to **deteriorate**, resulting in **slight but quantifiable clock speed discrepancies**.
Moreover, documents concerning the **Ceralock ceramic resonators** utilized in the SNES APU suggest that **temperature can influence their effectiveness**, indicating that a console’s APU might operate marginally faster as it heats up.
## Efforts to Resolve the Issue
To tackle the problem, Cecil swapped the **ceramic resonator in his SNES APU for a more precise quartz variant**, hoping this would restore flawless synchronization. However, the outcomes were **not as anticipated**. Even with an accurate quartz oscillator, the SNES still demonstrated **unexpected timing inconsistencies**.
Further investigation by **Rasteri**, another member of the TASBot team, indicates that the **SNES reset circuit** introduces extra randomness. Each time the console powers up, the **CPU and APU clocks begin at slightly different positions in their synchronization cycle**, resulting in **unpredictable timing fluctuations**.
## The Outlook for SNES Speedrunning
For speedrunners and TASBot developers, these revelations pose a considerable challenge. While **emulators can be modified** to address the real-world discrepancies in SNES hardware, achieving perfect **frame-accurate synchronization on actual consoles remains challenging**.
Despite these difficulties, Cecil and the TASBot team are dedicated to **understanding and alleviating** the SNES’s timing inconsistencies. Their research not only illuminates the **concealed flaws of retro gaming hardware** but also emphasizes the **complexity of attaining true hardware accuracy** in speedrunning.
## Conclusion
The identification of **APU clock variability in the SNES** presents a captivating
