Based on the well-known original memtest86 written by Chris Brady, memtest86+ is a port by some members of the x86-secret team. Our goal is to provide an up-to-date and completly reliable version of this software tool aimed at memory failures detection.

というわけで分家したらしいんだけど、2002-03-22以来更新されていなかった本家Memtest86も2004-03-11にv3.1aがリリースされてて、Added processor detection for newer AMD processorsとある。