An "All MAME ROMs pack" typically refers to a large collection of ROM files used with MAME (Multiple Arcade Machine Emulator) to emulate arcade games. These packs aim to include many — sometimes thousands — of arcade game ROMs and associated CHDs (hard-drive images) and BIOS files needed to run games in MAME.
The default MAME UI is clunky. Use a frontend like: all mame roms pack
Legal Status: Downloading ROMs for games you do not own is a legal grey area and typically violates copyright laws. Most "all-in-one" packs are hosted on community-driven archive sites rather than official storefronts. All MAME ROMs Pack — Overview & Guide
: Each game ZIP contains every single file needed to run, including parent and BIOS data. These are much larger but allow you to move a single ZIP file to another device without worrying about dependencies. Key Components of a Complete Pack Frontends (Don't Use Stock MAME UI) The default
If you cannot connect to the servers, check if you have some antivirus or firewall blocking the connection.