3 ms·
Hmm, so the purpose of memory scrambling is to avoid excessive current swings on the data bus, because they have some kind of undesirable effect on the voltage
by b161023ar 10y ago
Hmm, so the purpose of memory scrambling is to avoid excessive current swings on the data bus, because they have some kind of undesirable effect on the voltage regulator. I wonder if the result of such current swings is just excessive EMI or power consumption, or if the supply can actually go out of regulation. If you know the scrambling algorithm then you can generate those current swings intentionally...
- userbinator 10y agoI suppose you could get some interesting things to happen if you kick the control loop of the regulator into oscillation and set up some resonance; I wrote an old comment here, related to video cameras, that describes one such experience I had: https://news.ycombinator.com/item?id=9251479 https://news.ycombinator.com/item?id=9251479 It also reminds me of the old CD copy-protection schemes that worked by attempting to (and in a lot of cases, successfully) forcing the scrambling algorithm it uses to output difficult-to-write bit strings: https://www.pricenfees.com/digit-life-archives/magic-figures-detective-story-unreadable-cds https://www.pricenfees.com/digit-life-archives/magic-figures... http://www.cdmediaworld.com/hardware/cdrom/news/0102/sd2_truth.shtml http://www.cdmediaworld.com/hardware/cdrom/news/0102/sd2_tru...
- qb45 10y agoIt seems somebody reversed this Intel scrambler at least to some extent (I only skimmed the article): http://www.sciencedirect.com/science/article/pii/S1742287616300032#sec4 http://www.sciencedirect.com/science/article/pii/S1742287616... They suggest that the scrambler is reseeded randomly on every power up so it may be hard to control raw bits on the data bus.