The only (and strictly legal) way to obtain this file is through a process called "bios dumping." You take a physical SCPH-70012 console, use a homebrew tool like BIOS Dump Utility run via Free MCBoot, and copy the ROM to a USB drive.
Being an NTSC-U BIOS, it is strictly for North American game versions. You'll need a different file (like SCPH-70004 for Europe) to play PAL games at their native 50Hz.
As physical PlayStation 2 hardware ages, the optical drives fail and capacitors leak, rendering the consoles inoperable. The BIOS file represents a method of preservation. The scph-70012-bios-v12-usa-200.bin preserves the exact operational state of the PS2 Slim as it existed in 2004.
