3 ms·

How to unfuse it?

magicalhippo 3y ago
I don't know about this particular scenario, but typically fuses are small wires or resistors that are overloaded so they irreversibly break the connection. Hence the name. Either done during manufacture or as a one-time programming[1][2]. Though sometimes reprogrammable configuration bits are sometimes also called fuse bits. The Atmega328P of Arduino fame uses flash[3] for its "fuses". [1]: https://www.nxp.com/docs/en/application-note/AN4536.pdf https://www.nxp.com/docs/en/application-note/AN4536.pdf [2] https://www.intel.com/programmable/technical-pdfs/654254.pdf https://www.intel.com/programmable/technical-pdfs/654254.pdf [3]: https://ww1.microchip.com/downloads/en/DeviceDoc/Atmel-7810-Automotive-Microcontrollers-ATmega328P_Datasheet.pdf https://ww1.microchip.com/downloads/en/DeviceDoc/Atmel-7810-...
- HeatrayEnjoyer 3y ago
  Wires, flash, and resistors can be replaced
  - mschuster91 3y ago
    Not at the scale we're talking about here. These structures are very thin, far thinner than bond wires which is about the largest structure size you can handle without a very, very specialized lab. And you'd need to unsolder the chip, de-cap it, hope the fuse wire you're trying to override is at the top layer, and that you can re-cap the chip afterwards and successfully solder it back on again. This may be workable for a nation state or a billion dollar megacorp, but not for your average hobbyist hacker.
    - z33k 3y ago
      You’re absolutely right. In fact, some billion dollar megacorps use fuses as a part of hardware DRM for this reason.
  - magicalhippo 3y ago
    These are part of the chip, thus microscopic and very inaccessible. There are some good images here[1] of various such fuses, both pristine and blown. Here's[2] a more detailed writeup examining one type. It's not something you fix with a soldering iron. [1]: https://semiengineering.com/the-benefits-of-antifuse-otp/ https://semiengineering.com/the-benefits-of-antifuse-otp/ [2]: https://www.eetimes.com/a-look-at-metal-efuses/ https://www.eetimes.com/a-look-at-metal-efuses/
    - metadat 3y ago
      I miss the days when you could do things like connecting the L5 bridges on the surface of the AMD Athlon XP Palomino [0] CPU packaging with a silver trace pen to transform them into fancier SMP multi-socket capable Athlon MPs, e.g. Barton [1]. https://arstechnica.com/civis/threads/how-did-you-unlock-your-palimino.709631/ https://arstechnica.com/civis/threads/how-did-you-unlock-you... Some folks even got this working with only a pencil, haha. Nowadays, silicon designers have found highly effective ways to close off these hacking avenues, with techniques, such as the microscopic, nearly invisible, and as parent post mentions, totally inaccessible e-fuses. [0] https://upload.wikimedia.org/wikipedia/commons/7/7c/KL_AMD_Athlon_XP_Palomino.jpg https://upload.wikimedia.org/wikipedia/commons/7/7c/KL_AMD_A... [1] https://en.wikichip.org/w/images/a/af/Atlhon_MP_%28.13_micron%3B_overview%29.png https://en.wikichip.org/w/images/a/af/Atlhon_MP_%28.13_micro...
      - aceazzameen 3y ago
        I'm one of those folks that did it with a pencil. Haha. Maybe I was lucky? That was my first overclock and it ran pretty well.
mepian 3y ago
Use a Focused Ion Beam instrument.

How to unfuse it?

I don't know about this particular scenario, but typically fuses are small wires or resistors that are overloaded so they irreversibly break the connection. Hence the name. Either done during manufacture or as a one-time programming[1][2]. Though sometimes reprogrammable configuration bits are sometimes also called fuse bits. The Atmega328P of Arduino fame uses flash[3] for its "fuses". [1]: https://www.nxp.com/docs/en/application-note/AN4536.pdf https://www.nxp.com/docs/en/application-note/AN4536.pdf [2] https://www.intel.com/programmable/technical-pdfs/654254.pdf https://www.intel.com/programmable/technical-pdfs/654254.pdf [3]: https://ww1.microchip.com/downloads/en/DeviceDoc/Atmel-7810-Automotive-Microcontrollers-ATmega328P_Datasheet.pdf https://ww1.microchip.com/downloads/en/DeviceDoc/Atmel-7810-...

HeatrayEnjoyer 3y ago
Wires, flash, and resistors can be replaced
- mschuster91 3y ago
  Not at the scale we're talking about here. These structures are very thin, far thinner than bond wires which is about the largest structure size you can handle without a very, very specialized lab. And you'd need to unsolder the chip, de-cap it, hope the fuse wire you're trying to override is at the top layer, and that you can re-cap the chip afterwards and successfully solder it back on again. This may be workable for a nation state or a billion dollar megacorp, but not for your average hobbyist hacker.
  - z33k 3y ago
    You’re absolutely right. In fact, some billion dollar megacorps use fuses as a part of hardware DRM for this reason.
- magicalhippo 3y ago
  These are part of the chip, thus microscopic and very inaccessible. There are some good images here[1] of various such fuses, both pristine and blown. Here's[2] a more detailed writeup examining one type. It's not something you fix with a soldering iron. [1]: https://semiengineering.com/the-benefits-of-antifuse-otp/ https://semiengineering.com/the-benefits-of-antifuse-otp/ [2]: https://www.eetimes.com/a-look-at-metal-efuses/ https://www.eetimes.com/a-look-at-metal-efuses/
  - metadat 3y ago
    I miss the days when you could do things like connecting the L5 bridges on the surface of the AMD Athlon XP Palomino [0] CPU packaging with a silver trace pen to transform them into fancier SMP multi-socket capable Athlon MPs, e.g. Barton [1]. https://arstechnica.com/civis/threads/how-did-you-unlock-your-palimino.709631/ https://arstechnica.com/civis/threads/how-did-you-unlock-you... Some folks even got this working with only a pencil, haha. Nowadays, silicon designers have found highly effective ways to close off these hacking avenues, with techniques, such as the microscopic, nearly invisible, and as parent post mentions, totally inaccessible e-fuses. [0] https://upload.wikimedia.org/wikipedia/commons/7/7c/KL_AMD_Athlon_XP_Palomino.jpg https://upload.wikimedia.org/wikipedia/commons/7/7c/KL_AMD_A... [1] https://en.wikichip.org/w/images/a/af/Atlhon_MP_%28.13_micron%3B_overview%29.png https://en.wikichip.org/w/images/a/af/Atlhon_MP_%28.13_micro...
    - aceazzameen 3y ago
      I'm one of those folks that did it with a pencil. Haha. Maybe I was lucky? That was my first overclock and it ran pretty well.

mepian 3y ago

Use a Focused Ion Beam instrument.