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Old 27 February 2014, 10:36   #2
Toni Wilen
WinUAE developer
Join Date: Aug 2001
Location: Hämeenlinna/Finland
Age: 43
Posts: 20,638
MMU and cycle exact (or more compatible) is unsupported and can cause strange side-effects. MMU and cache emulation is not compatible (would require yet another CPU core, maybe someday..) and cycle exact without cache would make really slow 68030, especially if code is in chip ram.

SysInfo is correct and wrong, most 68EC030 CPUs have MMU that is not fully working (68030 with manufacturing error in MMU marked as 68EC030) or it is disabled but MMU instructions will still execute on 68EC030, they may not execute correctly or do anything at all (and in worst case it may simply hang the CPU) but they don't cause any invalid instruction errors. For compatibility purposes emulated no-MMU 68030 has dummy MMU instruction emulation.

68040/060 fixed this problem, MMU/no-MMU has official detection method and there is no side-effects.

EDIT: currently ticking cycle exact in 68030 MMU mode only enables chipset (=blitter) cycle exact emulation. CPU cycles are instant and won't be seen by chipset emulation = no dma contention at all.

Last edited by Toni Wilen; 27 February 2014 at 19:58.
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