[HN Gopher] Pulling Bits from ROM Silicon Die Images: Unknown Ar...
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       Pulling Bits from ROM Silicon Die Images: Unknown Architecture
        
       Author : mariuz
       Score  : 72 points
       Date   : 2021-03-22 15:23 UTC (7 hours ago)
        
 (HTM) web link (ryancor.medium.com)
 (TXT) w3m dump (ryancor.medium.com)
        
       | Scoundreller wrote:
       | Will give this a more thorough read later, but definitely has a
       | Chris Tarnovsky feel of what he had posted about paytv cards.
       | 
       | Whenever dealing with HF (hydrofluoric acid, not high frequency!)
       | make sure you have your calcium-based antidotes handy and get
       | yourself to a hospital if exposed. It's incredibly harmful, but
       | may not feel that way.
        
         | azalemeth wrote:
         | Indeed. HF causes life-long disfigurement and can be fatal. IV
         | calcium gluconate is the antidote in question, often prescribed
         | until ECG changes become limiting. It is a small ion and
         | literally eats your bones. I'm amazed you can buy it in a
         | product from Amazon in the US.
         | 
         | That warning aside, this article is _amazing_ --- very
         | insightful. I 've no idea how to begin reversing an unknown
         | architecture's firmware. I'm still not entirely sure I know the
         | point of this, but it's definitely fun...
        
           | Scoundreller wrote:
           | Industrially, I've seen calcium topical formulations as
           | something to hold you over.
        
       | 404mm wrote:
       | This is pretty mind blowing. I'm barely grasping the idea of
       | being capable of manufacturing something _this_ small. But
       | reversing the process is straight up there with unscrambling
       | eggs. Just wow.
        
         | PaulHoule wrote:
         | From an image processing perspective I think this is just like
         | reading a 2-d barcode like data matrix or QR or maybe reading a
         | punchcard.
         | 
         | Getting to the image though is an act of physical heroism that
         | he builds up to gradually (e.g. how can you really be so afraid
         | of H2SO4?) to the point where he is mixing acids with bleach at
         | which point I'm intimidated.
        
           | kens wrote:
           | Two things make extracting the data more complex than
           | something like a QR code or punchcard. First, the image
           | quality from a die usually isn't perfect. There are often a
           | few spots where it's hard to figure out visually, let alone
           | with software.
           | 
           | Second, the ROM layout isn't documented and there are a lot
           | of possibilities. Big-endian or little-endian? Is a
           | transistor a 1 or 0? What direction does the layout go? Are
           | columns or rows more significant bits? So you end up with
           | 2x2x2x... possibilities for interpretation. And that's
           | assuming the ROM layout doesn't have something entirely
           | unexpected, which happens quite often.
        
       | superfamicom wrote:
       | I was first introduced to this concept through emulation,
       | specifically Super Nintendo & Arcade work and would eagerly watch
       | change logs. It is amazing to see it really step by step, and
       | even now it still feels like magic.
       | 
       | - https://news.ycombinator.com/item?id=3675123
        
         | monocasa wrote:
         | Before them, flylogic was publicly documenting the same kind of
         | work in 2007.
         | 
         | https://web.archive.org/web/20080612172433/http://www.flylog...
        
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       (page generated 2021-03-22 23:01 UTC)