From the article: "Take a standard issue 7200 rpm, 500 GB _notebook SATA drive_. Add 4 GB of fast and reliable single-level cell (SLC) flash."
(Emphasis mine in both cases).
Besides that, it seems that the boot speed increase according to the article is next to non existent, and the comments point out that the application starts were actually done without wiping the OS cache.
From the article: "Take a standard issue 7200 rpm, 500 GB _notebook SATA drive_. Add 4 GB of fast and reliable single-level cell (SLC) flash."
(Emphasis mine in both cases).