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Comment by mmglr | Hacker News Reader

A few questions:

1. What was the intended use case behind the Tegra having 32 blowable fuses? Did Nvidia intend for those fuses to be used in this manner?

2. What is a non-retail switch?

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Fuses and OTP are a very common thing to throw in to systems. Most microcontrollers offer capabilities like this, and now they're drifting into more general purpose, larger SOCs. Maybe you use it to keep a serial number, or to separate product families, or for something like this.

Tegra's main purpose of the fuses is to handle holding cryptographic keys, boot parameters, and to disable the debug port. But since they have a fuse unit already, they provide a few words for the end-user to use as they please.

I too am curious what "non-retail" means in this context.

>I too am curious what "non-retail" means in this context.

Maybe dev kits? AFAIK Switch has at least two dev kits (SDEV/EDEV) for different purposes so it kinda makes sense to call them non-retail.

"non-retail" are usually either devkits, or units used for demo stands in shops.

Lots of system-on-chip devices have an array of fuses. Usually there's one for "permanently turn off JTAG" after factory testing, and most of the rest will be user-defined. Other uses include embedding serial numbers and cryptographic keys.

One common use case of the fuses is to prevent attack vectors which downgrade software to a vulnerable version. Using the OTP fuses older versions can be prevented from running to some extend.

1. Most likely - Switch isn't the first console which used fuses like this. Xbox 360 had them as well.

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