Back in the early days of computers, 80286 processors and 2400 BAUD modems were king. However, compared to what we have today, those former "speed demons" wouldn't even register on the ol' bandwidth Speed-O-Meter. As time passed, components got smaller and faster...yet it is never enough. We have an insatiable need for speed. But how far have we really come?
Speed is such a relative term. In order to understand how fast something is, there needs to be a baseline. For this article, the "lowly" 56k modem brings up the rear.
In order to compare bandwidth of such different sources accurately, factors like overhead need to be removed. Therefore, this article only compares the "theoretical bandwidth" of the different technologies. The folllowing chart list items like bus, memory and connection speeds.
Click here to see full size chart.
One item that you may notice is the lack of newer technologies (i.e. DDR2, GDDR-3, etc.) represented in the chart. There are a few reasons for this. In many cases, it was the lack of published standards. Second, there was a tremendous amount of conflicting information out there. And finally, it seems that manufacturers are setting their own speeds depending on the yields of the chips.
Here is an example of what Micron had to say about their DDR2
The evolutionary changes enable DDR2 to operate between 400 MHz and 533 MHz, with the potential of extending to 667 MHz and 800 MHz.
For PCI-Express, things get a little more complicated because it uses a lane architecture. Various types of hardware have different bandwidth requirements. Because of this, PCI-Express will launch in the form of two connectors, a single lane (x1) connector for Gigabit Ethernet and a 16 lane (x16) connection that will eventually replace AGP as the video card connection of choice. While that seems pretty clear, this bit from VIA shows how flexible PCI-Express is...and how confusing.
The VIA V-MAP Express architecture allows multiple device configurations, supporting connections of up to five PCI Express devices across a maximum 22 PCI Express lanes with a maximum theoretical bandwidth of 5.5GB/s.
VIA North Bridge solutions such as the PT890 for the Intel processor platform, and the K8T890 for the AMD processor platform, feature twenty PCI Express lanes, with 250MB/s of bandwidth per lane. PCI Express graphics will utilize 16 of these lanes for a dedicated 4GB/s connection. The remaining four PCI Express lanes in the VIA North Bridge provide 1GB/s bandwidth for two further PCI Express devices.
One purpose for doing this chart was simply see how far we've come in such a short period of time. As the ever increasing push for realism and access continues it ravenous appetite, we will see ever escalating needs for more bandwidth. In a few years, we will wonder how we got by with "outdated" technologies like SATA and DDR2.
It is my plan to revisit this chart every six months or so and bring it up-to-date with the latest specifications. In the current state of technology, even that may not be fatest enough!
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