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cb911

macrumors 601
Original poster
Mar 12, 2002
4,134
4
BrisVegas, Australia
my little brother reckons that it's impossible to have an exactly 167MHz bus without screwing up the computer, so he says that it's actually 166.66MHz. is that right?

please say that's wrong, so i can tell my bro he's wrong. :D
 
Re: 167MHz bus - actually 166.66Mhz?

Originally posted by cb911
my little brother reckons that it's impossible to have an exactly 167MHz bus without screwing up the computer, so he says that it's actually 166.66MHz. is that right?

please say that's wrong, so i can tell my bro he's wrong. :D

I am pretty sure he is right. (Just based off of the history of computers. 33.3Mhz bus, then 66.6 Mhz bus, then 100 (Which is really 99.99Mhz..)
 
Maybe it's the fact that the decimal mark isn't the same in all languages, so it's much easier just to round up.
 
The bus/processor speed multiple is 7.5, so either the bus is 166.66 MHz

1.25 GHz / 7.5 = 166.666 MHz

or it the processor speed is

167 MHz * 7.5 =1.2525 GHz

I'm not sure which one it is but both would work - maybe that would give you some wiggle room with your brother!
 
According to the processor info on my G3, it is a 67 MHz bus that is exact so it's the 400 MHz that is actually rounded down...not sure about the new G4, though.
 
The actual bus runs at 166.66 Mhz. The bus has to be right on with the processor. Computer companies, and programs that tell you your bus speed usually round the number up or down.

Now I will tell you that the computer doesn't operate exactly at the specified speed. It may vary , but usually not more than 1mhz in either direction. The bus is just set to run at a certain speed compared to the processor, so the bus depends on the processor to know how fast it has to run.
 
If you but a 2GHz system, do you think the processor is really exactly at 2GHz? Out of the same line, some will be faster and some will be slower. The slower ones typically get knocked down to the next slowest speed.
 
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