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Originally Posted by plasmab
Not the 6502 it doesn’t.
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It most certainly does. A 1MHz 6502 manages to copy about 2000b/50Hz frame, which is about 4000b/frame for a 2Mhz one. A 7Mhz 68000, as used in the Amiga, manages closer to 17000b/frame.
Which means the 68000 has faster memory access than the 6502 - even if the 68000 where to be slowed down to 2MHz, it would
still win for memory access speed.
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BBC B gets 0.5 mips at 2mhz. Same as the Amiga at 8mhz
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1) the 6502 uses 8 bits per instruction, the 0.5 mips figure for the 68000 is based on it running 32 bit instructions (it’s about 1 mips for 16 bit instructions).
2) even if it where true, the 68000 instruction set and 6502 instruction set are extremely different. Merely comparing intstructions per second for two architectures that are so different is just not going to work.
I’ll give just two examples:
1) a simple move.w d(an),d0 - a very common operation - takes just 12 cycles on 68000. The equivalent 6502 code (something like ldx #2; lda address,x; tay; inx; lda address,x) will take 14 cycles. Which is slower even clock for clock, let alone if it actually ran at 2Mhz vs 7Mhz.
2) divu or mulu are so much faster than even table based 6502 versions it’s not even funny.
There are plenty more examples here. Generally, the more you want your code to actually do, the bigger the 68000 advantage becomes.