Orchid XP v8 <voi### [at] devnull> wrote:
> andrel wrote:

> > Neither the 6510 nor the Z80 had a floating point processor. Floating 
> > point was in software.

> That's true. But assuming we want, say, a normal "double precision" 
> floating point number, how many clock cycles would you estimate it takes 
> to operation on? A dozen? A hundred?

  A lot. I don't believe *any* existing program for those processors
does double precision floating point calculations.

  As he said, I don't think the term FLOPS even applies if floating point
calculations are done in software instead of in hardware.

> > Both had a variable instruction set that took a variable amount of 
> > cycles to execute and therefor the number of instruction processed 
> > depended on the program and especially on the addressing modes used.

> I thought this was true for *all* processors?

  No. The idea with RISC processors is that each opcode has the same size
and takes exactly 1 clock cycle to execute. (Ok, granted, practical RISC
processors do have some opcodes which take more than 1 clock cycle to
execute because it would simply be a physical impossibility to perform
the operation in 1, but the vast majority are executed in 1.)

> Now, anybody have any clue "how big" the numbers are for less ancient CPUs?

  For Intel processors it depends a lot on the executed program and the
processor. With the 486 you might get something close if you divide the
clockrate with 1.5 (or something like that). With the Pentium and newer
it becomes very complicated (because the newer Pentiums have whacky things
like parallel pipelines and out-of-order execution).

-- 
                                                          - Warp

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