From: Gábor Lénárt (lgb_at_lgb.hu)
Date: 2005-04-22 08:09:50
On Thu, Apr 21, 2005 at 10:09:58PM +0200, A. Fachat wrote: > >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. > > > > > You must clear the flag in hardware. Because after the faulting opcode Yes. > the CPU writes data to the > stack and those accesses must succeed. Then it reads the interrupt > vectors to start the fault > routine. So when the NMI fault handler is taken it would be too late to > clear the flag. Hmmm, I've guessed - but I don't know - there is some pin of 6502 to sign NMI acknowledgment. If there is no such an ack signal it would be very problematic, I agree. > >Errrrrrrrrrrrr, what a mess at the end ;-) I think I've started to really > >overcomplicate the whole design :) > > > > > I guess that's why noone has so far - as to my knowledge - implemented > something like this :-) :) Well, it's time to syntetize a brand new 6502 core in fpga :) Welcome to the world of C=1. - Gábor Message was sent through the cbm-hackers mailing list
Archive generated by hypermail pre-2.1.8.