From: Gideon Zweijtzer (gideonz_at_dds.nl)
Date: 2005-04-22 06:58:26
> Gábor Lénárt wrote: > > > > >It can be solved anyway. In case of fault, a FlipFlop (FF for short) > >should be set. Any further memory operation (either > read/write) should > >be ignore by the MMU if that FF is set! In this way, we isolates CPU > >from the memory after a fault, to be sure that it will not corrupt a > >bogus memory locaton. The only task left is to clear that FF > after the > >opcode when the NMI taken, as fault handler. > > > > > It gets worse. The opcode in question could have updated an internal > register: > > $67ff and #$10 > > 67ff (and) gets pulled. > > $6800 is page fault, so force 0. Uh oh, as now .A is > corrupt, and there > is no way to reset it. > That same FF should also disable writes to the flags. Actually, the FF should disable any change to the internal state of the CPU. Gideon Message was sent through the cbm-hackers mailing list
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