TGO
Hype Train conductor. Works harder than it steams.
was gonna say, the discs are just cosmetically different and a normal CD drive in a PC reads them, but you pointed that out alreadyDrives can read CDs with a DVD frequency laser. The reason PC drives have a CD frequency laser is so they can read and write recordable CDs, as the dye in those only works at a certain frequency. For stamped discs, the data is encoded as physical pits, and all you need to be able to do is focus the laser beam to the size of the pits sufficiently, the frequency doesn't matter. Older DVD drives that just had the one laser could still read CDs, they just couldn't read CD-Rs.
The one piece of information I haven't managed to find yet is if the black layer on PS1 game discs is transparent to the red DVD laser (I'm assuming it's transparent to the CD laser's infrared). It might not be, but I would hope Sony didn't make a Playstation that can read any stamped disc ever made other than their own PS1 discs. But many PS1 games have CD audio tracks, so we'll know if it can read them as soon as CD playback is added.
Not having them read from Disc means 2 things
1, they are modified to would with PS4 or 2, Sony is just barring the ability to read from Disc
it's only changing the location it reads from from, the process for running the game is identical.