The Advanced Computing Environment (ACE) consortium was set up in the early 1990's by a number of companies to try and make a commodity computing platform based on MIPS processors as an alternative to the IBM-compatible Personal Computer based on Intel or Intel-compatible processors. The ACE consortium produced the Advanced RISC Computing (ARC) Specification (393K bytes, PDF), to specify hardware and firmware standards for this new computing platform. Unfortunately, the ARC platform failed to gain a critical mass of interest, and the consortium fell apart. The effort wasn't completely wasted; Microsoft was a member of the consortium and adopted much of the ARC specification for Windows NT, though Microsoft discontinued support for MIPS processors with the release of Windows NT version 4. The NetBSD Project supports these systems in NetBSD/arc. We make version 1.2 of the ARC specification (393K bytes, PDF) available with MIPS's permission, provided that we make clear that this is a historical document which the modern, post-SGI MIPS does in no way support.