guy@rlgvax.UUCP (Guy Harris) (09/25/84)
> Now, on a 68020, > > register foo() { ... > > makes a lot of sense. The 68020 has a 64-longword on-chip instruction > cache, and this instruction could be used to force a small function > into the cache *and keeping it there*. I am not certain of the exact > cache locking mechanism used (but I know there is one!), since a > friend just borrowed my MC68020 manual... Acccording to Section 7, "On-Chip Cache Memory", of the 68020 manual, you can turn on the "freeze cache" bit in the Cache Control Register with the MOVEC (Move Control) instruction; however, only system code can do that on a system which has supervisor and user states because the instruction is privileged. They say that "This bit (the Freeze Cache bit) can be used by emulators to freeze the cache during emulation function execution"; I think they are referring to code that handles the "line F" coprocessor instructions in software. Guy Harris {seismo,ihnp4,allegra}!rlgvax!guy