Explainer: How USB Works (and How It's Remained Ubiquitous and Ever Evolving)

QuantumPhysics

Posts: 6,271   +7,207
I actually prefer Lightning to USB-C, but I don't like the build quality of the lightning cables except for the newer heavy duty cables. If the contacts are dirty, it's easier to clean the Lightning heads.
 
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arrowflash

Posts: 514   +589
While USB is the less crap thing we have nowadays, I have always thought that USB sucks in general, and should have been replaced by a better standard long ago. There are too many different physical connectors (often unnecessarily so - in particular, I've never seen a sound reason for type B plugs to exist), all types of connectors are too flimsy and fragile and become error-prone with time, and power delivery across all USB types and revisions is too low which often is quickly compounded by connectors and cables degrading with time. These issues have significantly improved starting with USB 3.0 (USB 1.x was awful and 2.0 was terrible - USB 3.x is just mildly bad, so that's a big improvement) but are still far from ideal.

At least PS/2 and DB9 serial connectors and cables were a lot sturdier and more reliable than USB (parallel and SCSI not so much but still...)

I do think most of the criticisms on the original iMac at the time of its release were fair and justified. The lack of a 3.5 inch floppy drive or CD writer at a time when USB flash drives and external USB floppy drives didn't even exist yet, and the internet wasn't yet as ubiquitous, meant an original iMac G3 in 1998 was basically a doorstop only useful for content consumption in form of multimedia CD-ROMs or internet browsing, unless it was hooked to a corporate LAN. It was only successful thanks to Steve Jobs' reality distortion field.
 
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zamroni111

Posts: 304   +186
My college final project in 2002 was making VHDL codes of full spec USB 1.1 hub controller. Compilation took 10 minutes then another 5 minutes for simulation on pentium 3 desktop.?
 
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mattferg

Posts: 217   +227
Regarding USB 3.0 B - it is backwards compatible in exactly the same way A is - newer devices can use both 2.0 and 3.0 cables, main difference is speed, and older devices can only use the pins of older cables. You’d almost never be in a situation with a USB 3.0 B cable and a 2.0 device, but much more so the other way.

USB Mini A, Micro A and the combo Mini AB socket were almost never seen in the wild and haven’t been part of the standard for nearly two decades.

USB 4.0 isn’t on a ton of devices because the STANDARD was released last year. Like USB 3.0, which was only seen in 2010, two years after release. The real absence is 3.2 Gen2x2.

Speaking of, Thunderbolt has been rolled into USB - USB 4.0 IS Thunderbolt 3 and is fully interchangeable. Also, while we’re here - the Thunderbolt 1/2 connector wasn’t proprietary - it was Mini DisplayPort.

On top of this, FireWire 400/800 were never faster than USB 2.0/3.0 (400 vs 480 and 800 vs 5000 specifically) they were competitors to 1.1 and 2.0 respectively. The main draw was their lower latency for audio gear.
 
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Julio Franco

Posts: 8,856   +1,790
TechSpot Elite
Speaking of, Thunderbolt has been rolled into USB - USB 4.0 IS Thunderbolt 3 and is fully interchangeable. Also, while we’re here - the Thunderbolt 1/2 connector wasn’t proprietary - it was Mini DisplayPort.

On top of this, FireWire 400/800 were never faster than USB 2.0/3.0 (400 vs 480 and 800 vs 5000 specifically) they were competitors to 1.1 and 2.0 respectively. The main draw was their lower latency for audio gear.
Thanks for the feedback. There were a few mistakes on the article (particularly on the FireWire/Thunderbolt comparison), which we've corrected now.
 

p51d007

Posts: 3,096   +2,566
Do USB connectors still have the outside two pins (voltage & ground) longer/sticks out farther, to make sure the power is applied for the device, before any data connects?
 

neeyik

Posts: 1,881   +2,207
Staff member
Do USB connectors still have the outside two pins (voltage & ground) longer/sticks out farther, to make sure the power is applied for the device, before any data connects?
Yes, you can clearly see them in this USB-C image:

USB-Type-C-Connector-Pinout_0.png

Pins A1 and A12 are grounds, A4 and A9 are power. Since USB-C is rotationally symmetrical, the same is true for the B line of pins.