Emulation and the law: the emulator, the BIOS and the ROM are three different questions

This comes up on every game forum and the answers are usually confident and wrong. Here is the structure of the question under US law. It is general information, not legal advice for your situation. 1. The emulator itself Writing and distributing an emulator is generally lawful in the US. The two cases cited most are Sony Computer Entertainment v. Connectix (9th Cir. 2000), which held that reverse engineering the PlayStation BIOS to build the Virtual Game Station was fair use, and Sony v. Bleem (9th Cir. 2000), about Bleem's PlayStation emulator. An emulator becomes a problem when it includes copyrighted code from the console or is built to defeat copy protection. 2. The BIOS and firmware Many emulators need the console's BIOS or firmware. That code is copyrighted by the console maker. Distributing it is infringement. Dumping it from a console you own is the route emulator projects tell you to use, and the legality of even that depends on whether you had to break copy protection to do it, which brings in the DMCA's anti-circumvention rules. 3. The games (ROMs and ISOs) Downloading games you do not own the rights to is infringement, whatever the age of the game and whether or not you own the cartridge. "Abandonware" is not a legal category. Making your own copy from a cartridge or disc you own is the commonly accepted personal-use route, with the same circumvention caveat. What is clearly fine - Games the rights holder has released for free or put on official re-release services. - Homebrew games written for old hardware. - Preservation work done under the Library of Congress's DMCA exemptions for libraries and archives. Where to read more - Wikipedia, "Sony Computer Entertainment, Inc. v. Connectix Corp.": https://en.wikipedia.org/wiki/Sony_Computer_Entertainment,_Inc._v._Connectix_Corp. - The Video Game History Foundation works on preservation and access: https://gamehistory.org Other countries' rules differ. If you know your country's position, post it with the statute or case.