You had an older model PSX with the parallel port and a Gameshark Pro or similar device.
All these disc swap techniques work the same. The PSX only authenticated discs on boot or after the cover was closed, the latter being easily defeated with a piece of tape. If you could swap an authentic disc for a burned one after it had been authenticated, but before any of the actual data had been read, the PSX would run it. The cheapest option was to just force the motor to stop spinning by hand and swap discs at the correct time in the boot process. Cheat discs/devices like the Gameshark made this process easier because they would spin the drive down once you reached their menu and were designed to launch another disc when commanded so you didn't have to precisely time the swap.
All these disc swap techniques work the same. The PSX only authenticated discs on boot or after the cover was closed, the latter being easily defeated with a piece of tape. If you could swap an authentic disc for a burned one after it had been authenticated, but before any of the actual data had been read, the PSX would run it. The cheapest option was to just force the motor to stop spinning by hand and swap discs at the correct time in the boot process. Cheat discs/devices like the Gameshark made this process easier because they would spin the drive down once you reached their menu and were designed to launch another disc when commanded so you didn't have to precisely time the swap.