CompuServe Messages

Actually, it makes some difference whether you are using the 68451 MMU or the 68851 MMU. But actually, where most of my concern lies is the area of sharing areas of memory at other than the page level. In particular, chip memory on the Amiga is a problem. Chip memory is a resource that you would want to protect, but the Amiga design is such that you go in and directly fiddle it. Even if you don't, a defective Copper list can trash chip memory independently of any MMU (assuming that you can still modify a Copper list with a protected OS). To modify AmigaDOS to be completely secure, i.e., one task can not adversely affect another, would require a lot of effort in this area and would be very likely to not be fully compatible with current programs. Chris