MemTest86 History - from 1994
MemTest86 was originally developed by Chris Brady (BradyTech Inc) with a first release in 1994. However, some of the testing algorithms used have been under development since 1981 and have been previously implemented on Dec PDP-11, VAX-11/780 and Cray XMP architectures. Since then there has been more than a dozen new versions being released. Support for 64bit, new CPU types, symmetrical multiprocessors and many other features have been added during this period. MemTest86 was released as free open source (GPL) software.
MemTest86 and MemTest86+
During the time period of the MemTest86 V3.0 release (years 2002 to 2004) the code was 'forked' by Samuel Demeulemeester (now part of the French CanardPC publishing group) into a another version of the software called MemTest86+. The naming was unfortunate as it now leads to no end of confusion among users. Neverthless both Memtest86s subsequently continued to be developed. With the feature set of MemTest86+ V5.0 and MemTest86 V4.3 being approximately equal in 2013. Also in 2013 a proposal was made to re-merge to two code streams into a single package, but it was not to be.
MemTest86 the new era
In Feb 2013, PassMark Software took over the maintenance of the MemTest86 project from Chris. This was around the time that a lot of technological changes were occurring. The 64bit era was here, DDR4 was coming, UEFI had already arrived and Microsoft's Secure boot technology threatened to prevent MemTest86 from booting on future PC hardware.
Starting from MemTest86 v5, the code was re-written to support self booting from the newer UEFI platform. UEFI is able to provide additional services that is unavailable in BIOS, such as graphical, mouse and file system support. Support for DDR4 & 64bit were also added and Microsoft agreed to code sign MemTest86 for secure boot. The software (Free Edition) still remains free to use without restrictions. The MemTest86 v4 project is still maintained and remains open source, for use on old machines with BIOS. From V5 however the software is being released under a proprietary license. For advanced/enthusiast users or commercial applications, a professional version is available for users that require additional customizability and advanced features that may be more suitable for their testing needs. A comparison of the different versions can be found here. We have also created a support forum where users can discuss issues.
Detailed release history
A detailed list of changes in each release can be found on the MemTest86 release history page.