A lot of people associate PSX with the PlayStation X, the codename of the first Sony Playstation. Did you know the PSX is actually released exclusively in Japan on december 2003? The PSX is a digital video recorder with a built-in PlayStation 2 being capable of running original PlayStation and PlayStation 2 games.
It was the first Sony console to have the famous XMB, CrossMedia Bar menu structure.
Information:
https://en.wikipedia.org/wiki/PSX_(digital_video_recorder)