Memtest86, a popular software for RAM diagnostics, was initially developed as open source (GPLv2). Version 3 was forked into a separate project, Memtest86+, also distributed under GPL terms. Source code of Memtest86 v4.3.7 is distributed inside the corresponding binary image.
However, Memtest86 v5.0 and up suddenly became closed-source software, property of PassMark Software Pty Ltd. How could this happen? Could Chris Brady (the original Memtest86 author) somehow give them exclusive rights to the code, or did they have to re-write the software from scratch? And if they did, how could they keep the name? Am I allowed to write my own closed-source version of e.g.
grep, and distribute my program under the same name?
It seems that
grep is trademarked, but any name will do for the sake of argument.
thttpd is clear, for example, and so is