Bus speeds
I want to know everything there is to know about bus speeds. Well, maybe not EVERYthing...
Anyway, the fast bus speeds on any Mac is 133MHz, on the Xserve, PowerMac, and PowerBook. iMac and iBook are still @ 100MHz. Isn't that slow on the PC side? How important IS bus speed if Apple seems to take forever to upgrade the speeds?
On the tech specs for the Xserve, they say: "133MHz system bus supporting over 1GB/s data throughput"... what does the 1 GB/s of throughput mean? Is that just normal for a 133MHz bus, or has Apple increased the throughput without increasing the MHz?
Finally, I hear this stuff about Double Pumped and Quad Pumped busses. What are those, and will they be implemented on the Mac?
Anyway, the fast bus speeds on any Mac is 133MHz, on the Xserve, PowerMac, and PowerBook. iMac and iBook are still @ 100MHz. Isn't that slow on the PC side? How important IS bus speed if Apple seems to take forever to upgrade the speeds?
On the tech specs for the Xserve, they say: "133MHz system bus supporting over 1GB/s data throughput"... what does the 1 GB/s of throughput mean? Is that just normal for a 133MHz bus, or has Apple increased the throughput without increasing the MHz?
Finally, I hear this stuff about Double Pumped and Quad Pumped busses. What are those, and will they be implemented on the Mac?
Comments
The bus speeds on PCs are the same. Whenever you see those '266MHz' bus speeds, that is just a 133MHz bus that is using DDR technology. This means that the bus is sending AND receiving on each clock cycle, which effectively doubles the speed with out really doubling the speed. 100MHz bus IS slow on the PC side since most PCs support DDR and most of the old systems that aren't DDR are just 133MHz, but there are lots of people that have old computers out that and 100MHz vs 133MHz on the same system isn't enough of an increase that normal Joe or Jane user would notice the difference unless they were into the latest and greatest games.
On the tech specs for the Xserve, they say: "133MHz system bus supporting over 1GB/s data throughput"... what does the 1 GB/s of throughput mean? Is that just normal for a 133MHz bus, or has Apple increased the throughput without increasing the MHz?<hr></blockquote>
133MHz means frequency with which the bus transmits data. 133MHz bus transmits data 133 million times per second. Throughput on the other hand depends on the bandwidth that the bus has. The bandwidth determines how much data can be sent each time that the bus sends data. The bandwidth multiplied by the frequency tells you how much data can get sent per second ( since it is sending the maximum amount of data so many times per second ).
[qoute]Finally, I hear this stuff about Double Pumped and Quad Pumped busses. What are those, and will they be implemented on the Mac?
I don't know what double or quad on a technical level ( tom's hardware says that the p4's 'quad-pumped' uses the same principle as AGP4x and I'm not that knowledgable on the specifics of AGP ). But I do know that when you do the calculation you do this:
Throughput = bus width x frequency x pump multiplier
quad-pumped would have a 4 for the 'pump multiplier' ( not sure the exact term ) , and double-pumped would be 2 and so forth.
Hope this helps.