Boot the ROM. On the N64 logo screen, before the title appears, there is a hidden debug string. Version 1.0 shows a specific date code indicating a mid-1998 build. (Specific text strings: Look for 1998-07-14 build date on the debug ROM).
For the Ocarina of Time speedrunning community, the 1.0 ROM (Z64) is the standard. Why? Glitches. Later versions patched out iconic exploits such as: Ocarina Of Time 1.0 Rom Z64
The only strictly legal method is to buy an original Version 1.0 cartridge (typically the gold Collector’s Edition) and dump the ROM yourself using a specialized device like a RetroBlaster or Sanni Cart Reader . This creates a personal backup—which, while still legally contested, is generally accepted in preservation circles. Boot the ROM