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RE: Enough Computer Audio Mythology

Posted by Tony Lauck (A) on December 15, 2014 at 13:06:45

In Reply to: RE: Enough Computer Audio Mythology posted by SBGK on December 15, 2014 at 12:25:38:

Each bit in DRAM is stored in a tiny capacitor. This capacitor is charged with a small number of electrons. Below a certain number it's a 0. Above that number a 1. There is a dedicated capacitor for each bit and a transistor that serves as a switch to connect this bit onto a sense wire, where the number of electrons can be measured. Now the problem is that the electrons slowly leak away for various physical reasons. (This depends on the temperature of the substrate, residual radioactivity, etc...) If there were initially a large number of electrons that represented a 1 then after leakage they may enter in to the ?? range, or even leak down to look like a 0. To deal with this problem, there is a memory controller. It reads every memory location (refresh operation) about once a second. Each bit that is read is rewritten back so that it is close to the ideal number of electrons for a 0 or a 1. This is the equivalent to looking at a smudged image by eye and recopying on a clean piece of paper.

It seems most unlikely that hidden information will survive after a few seconds of recopying. It seems much more likely that the data in RAM is not identical in the two test cases, or that there is data stored elsewhere in the computer system that is different. It is possible to compare the contents of RAM memory by loading special software with a special boot loader program, but probably not all other parts of system state. I would expect things like processor cache may differ and this may have important implications on system performance. Unfortunately, these factors depend on the specific processor and motherboard models.

There are many ways to explore this rabbit hole in depth. However, IMO unless the entire contents of RAM is validated to be identical in the two cases there is little point in proceeding further. I recall the WAV to FLAC to WAV vs. original WAV issue. At first glance, the audio samples in the two WAV files were identical, but after investigating further, the two files were not identical, as their meta-data differed. I see no reason to believe this case is any different.




Tony Lauck

"Diversity is the law of nature; no two entities in this universe are uniform." - P.R. Sarkar

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