You see, if you knew even half as much about the design of the original Amiga hardware as you try to impress upon us in threads like this, you'd know that the 68000 was as integral to the design of the system as any of the custom chips.
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I never tried to impress upon anyone my knowledge of Amiga hardware. Perhaps, that's what you are trying to do. I was just asking someone about Pegasos which I never heard of before. I don't have any 68060 system so I stated my comments with "if".
>So, to suggest that the 68000 was not an integral part of the overall hardware design, is frankly bollocks.
If you did not rely on the timing of the 68000 in your code and just relied on the instructions getting executed and used the CIA, Copper, and other timers for the timing, then it shouldn't matter if it's 68000, 68020, or other backward compatible processor.
>Faster CPU's only work in there thanks to the Fast RAM side of the design. The moment you put even a 68020 into the original design, without Fast RAM, it is crippled. It doesn't fit into the original one access every 2 cycles design as it is capable of a memory access every cycle and is thus forced to wait. Even with Fast RAM, thanks to the instruction cache, it's also no longer compatible with just "any old" 68000 code. Anything self modifying is doomed to fail spectacularly since the instruction cache is never, ever written to by data writes.
The 68020 is still called backward compatible with 68000 just like Pentium is backward compatible with 8088 although it has similar problems with caching.
>So, by your argument any Amiga that has a 68020+ is not perfectly backwards compatible with the original OCS design and is therefore not a real amiga.
No, you still write to the same hardware registers on 68020+ and get the same results.
>The problem just gets worse with every faster 680x0. The 030 even has a data cache. That totally craps on the original DMA system unless you turn it off for the 24-bit DMA region. Which is exactly what they had to do.
I don't think you understood my argument-- if you use 68000 to time your code instead of other generic timers, then that means that emulator should be able to that same timing. If you write general code that works across all 680x0 processors, then you can't be relying on the timing of the processor.
>With the 040 and especially 060, you even have to start emulating several instructions. Emulation? Surely that's no better than UAE :rolleyes:
I don't see how that affects the timing. If you do LOOP instruction in 80x86, it takes more cycles than doing DEC/Branch but earlier processors had it the other way.
>In short, all this talk of "doing everything the exact sane way a real amiga does it" is total drivel because most actual physical amigas do things that are completely outside the original 68000/OCS design.
If you rely on those 680x0 specific timing features, then those timings should be exact as well.
