How The Speed of My Eyeball Affects Computer Design
There is an interesting relationship between the bandwidth of the human optic nerve and the evolution of computer architectures.
Early timeshare systems had way too little bandwidth between the computer and the user. Way, way less than the bandwidth of my eye. As a kid, I remember playing the computer game Star Trek on a 300 baud modem. The "long range scan" was painfully slow, even though all it printed was a 10 by 10 array of letters showing the current sector in space. (E is for Enterprise; K is for Klingon.) Later, when I got my first programming job, my terminal was 1200 baud—only senior engineers rated 2400 or 4800 baud terminals. Still painfully slow.
Networks and terminal cables were so slow that the only way to get quality graphics was to put the CPU right in front of the user's face—hence the invention of the workstation. That was a big improvement, but computer graphics were still much slower and blockier than real life. Computer games provide good intuition about this. Think back to the flight simulators of ten years ago. Today, CPUs and graphics cards have improved so much that improvements are marginal. The latest generation of games has slightly better flames and smoke, and I can see individual hairs on the characters, but it doesn't really make a difference.
Once the CPU and graphics card have bandwidth that matches my optic nerve, further improvements simply don't matter.
Likewise, once the network bandwidth approaches the bandwidth of the optic nerve, there is no longer any reason to keep the CPU close to the user's face. For most applications, we've already reached this point, which is why CPUs are starting to recentralize. One of our customers told me that he is moving most of his users to Citrix thin clients, with the PC itself centralized on blade servers, probably running VMware. He won't be moving his power users at first, but as networks get faster, there is no reason he shouldn't.
It is interesting to consider Moore's law in the context of fundamental human limits like optic nerve bandwidth. I think everyone understands that CPU performance is getting less and less important for most applications. That's why I care more about weight and battery life in my new laptop computer than I do about CPU speed. But as computer and networking performance passes the physiological limits of people, it becomes clear that applications where performance matters will become more and more esoteric.
I certainly don't mean to suggest that it's time to stop making faster computers and networks. Plenty of scientific and corporate applications need more speed. However, considering human limits, we can see that for the majority of applications, it's going to be more important to focus our innovation on cost and convenience.
Early timeshare systems had way too little bandwidth between the computer and the user. Way, way less than the bandwidth of my eye. As a kid, I remember playing the computer game Star Trek on a 300 baud modem. The "long range scan" was painfully slow, even though all it printed was a 10 by 10 array of letters showing the current sector in space. (E is for Enterprise; K is for Klingon.) Later, when I got my first programming job, my terminal was 1200 baud—only senior engineers rated 2400 or 4800 baud terminals. Still painfully slow.
Networks and terminal cables were so slow that the only way to get quality graphics was to put the CPU right in front of the user's face—hence the invention of the workstation. That was a big improvement, but computer graphics were still much slower and blockier than real life. Computer games provide good intuition about this. Think back to the flight simulators of ten years ago. Today, CPUs and graphics cards have improved so much that improvements are marginal. The latest generation of games has slightly better flames and smoke, and I can see individual hairs on the characters, but it doesn't really make a difference.
Once the CPU and graphics card have bandwidth that matches my optic nerve, further improvements simply don't matter.
Likewise, once the network bandwidth approaches the bandwidth of the optic nerve, there is no longer any reason to keep the CPU close to the user's face. For most applications, we've already reached this point, which is why CPUs are starting to recentralize. One of our customers told me that he is moving most of his users to Citrix thin clients, with the PC itself centralized on blade servers, probably running VMware. He won't be moving his power users at first, but as networks get faster, there is no reason he shouldn't.
It is interesting to consider Moore's law in the context of fundamental human limits like optic nerve bandwidth. I think everyone understands that CPU performance is getting less and less important for most applications. That's why I care more about weight and battery life in my new laptop computer than I do about CPU speed. But as computer and networking performance passes the physiological limits of people, it becomes clear that applications where performance matters will become more and more esoteric.
I certainly don't mean to suggest that it's time to stop making faster computers and networks. Plenty of scientific and corporate applications need more speed. However, considering human limits, we can see that for the majority of applications, it's going to be more important to focus our innovation on cost and convenience.
Comments