Posted By
JamesD
on 2013-08-02
18:12:52
|  Re: Z80 GUI: SymbOS
@MMSZ
MIPS on processor A <> MIPS on processor B unless they are a similar architecture.
Remember RISC requires more instructions to do the same thing as CISC so counting how many million instructions per second isn't going to give an accurate speed comparison.
And attaching a 50MHz eZ80 to a <2HMz 6502 buss is going to be real interesting to say the least. I was suggesting just using the +4 clock and letting the eZ80 optimizations make up for the slow clock speed.
The Trex machine uses a CPU core with Z80 timings so I'm not surprised about the MP3 playback. The 24MHz Trex is a very different beast than the 25MHz CoCo 3. If they switched cores to the pipelined Z80 I mentioned then it would run much faster. Still not sure about MP3.
@Litwr
Every Z80 machine you mentioned in your last post has different wait states. But if you compare to that, you are comparing to a specific machine, not just the Z80.
As for the s1,s2, I was relating to my earlier post where I was talking about previous benchmarks I'd seen, not your code sample. You said a difference of 1 clock cycle but you weren't talking about the same thing I had been talking about. You didn't take as many shortcuts on this benchmark as some of the previous ones I had seen.
FWIW, RISC isn't very comfortable for a human. It involves moving simple instructions around to prevent pipeline stalls and it's a bit tedious. For an embeded system I worked on we generated code for the DSP with a compiler and then did some hand optimization. Compiler optimisers weren't that great yet. A decent peephole optimizer could have done the same thing in seconds.
gerliczer@
I'm familiar with that Z80 vs 6502 thread. It was more about WHY the 6502, Z80 or other CPU and not bragging rights over benchmarks.
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