DRM refers to the fact that you can't view Amazon Kindle books on other devices (including your computer), or on other Kindles - i.e. no sharing, the purpose of DRM.
The Kindle DRM wasn't hacked to REMOVE the DRM from Kindle purchases, but added to other books so that they too could be read on the Kindle.
There are converters available from Amazon and/or Mobi for pdf and doc files.
Use Mobipocket software to convert PDFs to that format so you can read them on Kindle.
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