As computers and global computer networks continued to advance and emulator developers grew more skilled in their work, the length of time between the commercial release of a console and its successful emulation began to shrink. Fifth generation consoles such as the Nintendo 64, the Sony PlayStation and sixth generation handhelds, such as the Game Boy Advance, saw significant progress toward emulation during their production. This has led to a more concerted effort by console manufacturers to crack down on unofficial emulation. Both country specific copyright and patent law and international copyright law under the Berne Convention protect copying and reproducing of subject matter with copyright protection.
Under United States law, obtaining a dumped copy of the original machine’s BIOS is legal under the ruling Lewis Galoob Toys, Inc. v. Nintendo of America, Inc., 964 F.2d 965 (9th Cir. 1992) as fair use as long as the user obtained a legally purchased copy of the machine. However, several emulators for platforms such as Game Boy Advance are capable of running without a BIOS file, using high-level emulation to simulate BIOS subroutines at a slight cost in emulation accuracy.