CHD is lossless —you lose nothing. "Rip" versions found on some sites might remove music or cutscenes to save space; avoid these if you want the full experience.
For PlayStation 1 games, there are three primary formats that significantly reduce file size without losing game data: Ps1 Roms Highly Compressed
: Originally the format used for PS1 games on the PSP. It's great for multi-disc games Final Fantasy VII CHD is lossless —you lose nothing
Originally created by Sony to allow PS1 games to play officially on the PSP. It's great for multi-disc games Final Fantasy VII
Original PS1 games were distributed on CD-ROMs. When these discs are copied to a computer, they create an identical digital image. Understanding the standard formats helps explain why compression is so valuable. Standard PS1 Dump Formats
Downloading copyrighted ROMs for games you do not own is considered copyright infringement in most jurisdictions (US, EU, Japan). However, laws vary, and "Abandonware" is not a legal defense.