[HN Gopher] Two dies in one package: Teardown of a vintage ROM w...
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       Two dies in one package: Teardown of a vintage ROM with double the
       storage
        
       Author : parsecs
       Score  : 47 points
       Date   : 2021-03-22 17:34 UTC (5 hours ago)
        
 (HTM) web link (www.righto.com)
 (TXT) w3m dump (www.righto.com)
        
       | kens wrote:
       | Author here if anyone has questions about vintage IBM integrated
       | circuits :-)
        
         | marcodiego wrote:
         | Does the metal can packaging make the chip less vulnerable to
         | static or fields? I mean, does it work somewhat like a Faraday
         | cage?
        
         | spaceribs wrote:
         | Really cool! I assume it would be possible to take the pictures
         | you have, turn them into 1s and 0s via some sort of image
         | processing, then pop out actual code?
        
           | kens wrote:
           | Yes, it would be straightforward to extract the data from
           | these ROM images. (See the "Pulling Bits from ROM Silicon Die
           | Images" article currently on the HN front page.)
           | 
           | I extracted some of the data from the ROM, but it wasn't
           | anything obvious. I didn't spend a lot of time examining the
           | data since it's probably something like microcode for an
           | undocumented IBM control processor. The extracted data did
           | let me verify that the 9 bits were 8 + parity.
           | 
           | To extract the bits, I made a simple JavaScript program where
           | I click on the transistors. For a small amount of data, this
           | is faster than performing image processing and setting up
           | automated analysis software.
           | 
           | One problem is that once you get the bits, there are a lot of
           | uncertainties. Is a transistor a 0 or 1? What order are the
           | bits in? Are the addresses left to right or right to left? So
           | you end up with a bunch of cases you need to consider, rather
           | than a nice hex file.
        
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       (page generated 2021-03-22 23:01 UTC)