OpenBSD on Motorola 88000 processors

Summary

(Follow this link to go back to the main m88k page.) PART 1: The Forsaken RISC Architecture No, it's no typo Many people know, or have heard of, the Motorola 68000 architecture. These processors have been used in many machines: in the first generations of Apple Macintosh computers, in the ever-rivals Amiga and Atari ST home computers, in many workstations built by Sun, HP and NeXT (to name only a few), but also in many industrial systems and boards built by Motorola, Tadpole, Heurikon or Performance Technologies (to name only a few.) The 68000 architecture has been very successful, but due to its CISC nature with complex addressing modes and many instructions, Motorola was not able to keep up in the speed competition. In order to be able to deliver performance and megahertz, another processor architecture was needed, one which could scale more easily. At this point you're probably expecting me to write about the PowerPC, which also turned out to be a successful architecture, used in the next generations of Apple Macintosh computers, in workstations (from IBM and Bull, mostly), and in the iconic BeBox. But between the 68000 and the PowerPC, there's the black sheep of the family. A processor architecture which made a lot of promises, but did not deliver them, and was destined to be consigned to oblivion, as if it had been a bad dream. That processor architecture is the Motorola 88000 architecture, or m88k for short. m88k in a nutshell There have been two generations of 88000 processors before Motorola reassigned all its engineers to the PowerPC. The first generation consists of the 88100 CPU, with optional external 88200 so-called CMMU: a chip which provides both cache memory and memory management facilities. The choice of separate chips allowed designs which did not need an MMU to be completed quickly and cheaply, and NCD used the 88100 a lot in its X terminals line for that reason. All the CMMUs sit on the same so-called P-Bus with the processor, and work closely wi...