A: Yes! Tools like CHDMAN (for CHD format) and maxcso (for ZSO format) allow you to compress your existing ISO files. Just search for tutorials on how to use these free tools.
This comprehensive guide explores the world of highly compressed PS2 ISO files, explaining how compression works, how to safely find and extract these games, and how to optimize them for seamless emulation. Understanding PS2 ISO Compression ps2 highly compressed games iso link
Emulators require PS2 BIOS files to function. A BIOS acts like the console's operating system. You can legally dump BIOS files from your own PS2 console. Downloading BIOS files from unofficial sources is generally considered illegal. A: Yes