What do you mean R800 is 16-bit processor?

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By sjoerd

Hero (593)

sjoerd's picture

03-05-2003, 18:33

Ok, I think it's about time to wrap this discussion up... conclusions?I do not seem to come to the same conclusions Smile Stange enough...

- There is no 'pure' RISC processor as of yet, so actually no processor can be called RISC for that matter. However, a processor can be RISC-based. Depending on your standards, the R800 is RISC-based. (or not)There probably never will be a pure risc cpu, the cisc versus risc debate is over; cisc won. I am wondering how the R800 executes a instruction every cycle without a pipeline...

- From the experience of at least one coder who has experience with optimized coding for both the R800 and the Z380 we can conclude that the one-instruction-per-cycle setup of the R800 generally results in a relatively larger speed-gain than the advantage of a 16-bit Z380 running on a higher clock. Some instructions are indeed a lot faster than on a R800 but in practical situations the R800 still wins... most of the time.According to GuyveR800: R800 at 7MHz is as fast as a Z380 at 14MHz. The Z380 is faster when using mul/div instructions.
And I am not convinced that Z80+Z380 is slower than just a Z80.

- The R800 can handle 16 bit numbers. It has 16 bit registers, a 16 bit ALU, has 16 bit adressing space yet is connected to an 8 bit databus. To me, that makes it a 16 bit processor. A Ferrari engine in a Trabant still makes it a Ferrari engine.That makes it a wasted ferrari engine...

I think both GuyveR and sjoerd have said what they had to say on this subject. Instead of going round in circles and pointing to things already said before I think it's best to see if other people have something to say about this.Asking about that pipeline thing is not running in circles...

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