| Subject: RE: Ideas on new Atari |
Author: Evan Langlois (67.187.51.187)
Date: 03-12-2005 07:47
Good question. Which RISC CPU would you use? It would depend on your needs? Do you want fastest possible speed with no backwards compatibility? G5s? Is price a concern? If so, forget G5s. If code size is an issue, forget anything in the x86 line, no matter how fast. Likewise with power consumption! PowerPC is hungry, and x86 is even hungrier.
Now, Coldfire is RISC. What else would you recommend? XScale? PowerPC?
For power consumption coldfire and Xscale are your main choices. PowerPC won't cut it. Also, the instruction sizes on coldfire can be much smaller than PowerPC. A PowerPC may average 2 instructions per bus fetch, it does so with a 64 bit bus as instructions are 32 bits wide. On Coldfire, the instructions can be 8, 16, or 32 bits wide, so you can often get the same 2 instructions per fetch on a 32 bit bus.
Now, when you look at the efficiency of running an emulator for older code and the growing pains Amiga sees now, and Apple saw with 68K to PPC and later with OS9 to OSX, the idea of using coldfire and running most of the code native becomes very attractive. Code compiled for a coldfire is also backwards compatible to the 020 and up! 68K code can run on coldfire with either a library for the missing instructions or with a 68K->Coldfire assembly translator. Either way is much cleaner than full CPU emulation.
I looked at Coldfire first because of its own merits (okay, and I really like the 68K design being the second assembly I learned, right after 6502). The fact that a great musician friendly OS and apps that I was already familiar with is icing on the cake.
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