>> 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.

You're probably right about that. (Just moving 8 bytes around has to 
take a minimum of 8 instructions, before you *do* anything to those 
bytes.) Just wanted to make it a like-for-like comparison. ;-)

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

Floating-point operations per second. Does it matter *how* it does them? 
Surely the important point is how many of 'em it can do.

>>> 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.

Interesting. I was under the impression that processors such as the 
Pentium can execute multiple instructions in parallel, and therefore 
several instructions can reach the "completed" stage in a single given 
clock cycle, but that each individual instruction still takes multiple 
cycles from start to finish.

>> 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).

I'm only trying to figure out "how many zeros" are in the number, if you 
see what I mean...

Is it 10 MIPS? 100? 1,000? 1,000,000??

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

Post a reply to this message