[HN Gopher] Two dies in one package: Teardown of a vintage ROM w... ___________________________________________________________________ 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. ___________________________________________________________________ (page generated 2021-03-22 23:01 UTC)