My blogs on USB seem to have sparked a flurry of interest and responses...
I've said it before and I'll say it again: "It's a funny old world sometimes!" The reason I say this is that I occasionally post a "provocative" blog to which I expect to see a lot of feedback... and nothing happens. By comparison, I might post a column on something I consider to be relatively innocuous, only to be bowled over by a deluge of feedback.
With regard to this latter scenario, my recent musings on USB (see blogs #210200029 and #210201213) provide a classic example. USB-related messages are "pinging" their way into my email fast and furiously, such as the following which arrived just a few minutes ago as I pen these words:
Hi Max, One thing I didn't see you mention in the history of USB was that this bus was touted as how one would have a totally wired house, i.e. appliances and such controlled by a PC to do all kinds of things.
The way forward was the fact that a single USB port was capable of hooking up 127 serial devices. That seems to have been forgotten with everything made that works with USB. I have yet to see any USB device besides a HUB have both and input USB connection and a daisy chain output port for the next device.
What happened here? This is why we now find new PCs with 4-8 ports on the back, internal headers to connect to some number of front of case ports, and typically one or two additional internal headers that could be connected up front side or out the rear for even more ports. The promise of a bus that would allow 127 devices per port obviously got lost in the rush to speed up the bus and in the devices that the various manufacturers decided they didn't have the space or needing to save costs, couldn't afford the output port to connect up the next device.
One of the first devices, the mouse, was an item that having this additional cord potentially attached for the next item in the chain made little sense as it may interfere with mouse movement. As more devices were added with their very small form factor such that the daisy chain port wouldn't fit, or even the original interface connector (that big, sort of square-ish connector) the USB connection on the peripheral migrated to these dinky little connections and again, daisy chaining was not an option.
Today, no one even mentions or mostly even remembers one of the big promises of the original USB bus, the ability to connect lots of devices in a daisy chain. Speed wasn't the issue as all of the devices were "Human Interface Devices" like household appliances and such, none of which needed any speed.
Do you know, I'd forgotten all about the USB daisy-chaining idea. Rather than having hubs scattered around all over the place (or maybe "in addition to"), there are many occasions when it would be handy if you could simply plug the output from one USB device into the input of another.
On the other hand ... it might not be too long before Wireless USB takes over the world, and having cables with USB connectors on the end is regarded as being a tad gauche and "So early 2000s, my dear!"
Questions? Comments? Feel free to email me – Clive "Max" Maxfield – at email@example.com). And, of course, if you haven't already done so, don't forget to Sign Up for our weekly Programmable Logic DesignLine Newsletter.