An important difference in ATOMIC compared to Techtool Pro is that it maximizes available free memory prior to testing. In TechTool Pro, only available free memory at that time is tested. It doesn’t (yet) clean up remnants of free memory which the system holds for recently-launched applications. By forcing a cleanup (or purge) of this memory, ATOMIC can test a much larger amount of free available memory than TechTool Pro.
The idea was inspired by testing older Macs in our lab. Some of these Macs only have 2GB of physical RAM installed, and Techtool Pro would consistently test as little as 35MB to 600MB of memory during its Memory Test. The only way we could test more was to reboot it and then immediately launch TechTool Pro and immediately start the Memory Test.
With ATOMIC, we don’t need to reboot the computers anymore because it can reclaim unused memory. Now, when we test Macs with 2GB of RAM, we consistently test much larger amounts of RAM: 1.4GB of 2GB. On other Macs with more memory, for example, 8GB, 6.5GB is tested using ATOMIC. TechTool Pro’s Memory Test may reach up to 6.5GB on occasion, but it’s typically less.
And of course, ATOMIC contains five additional (and much more thorough) memory testing algorithms which the current version of TechTool Pro does not have.