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Rouxenator
Dank meme lord
USB1 and USB2 only has one data line consisting of two wires. USB3 has 3 data lines consisting of 6 wires, so therefor it is actually parallel. Why do they still call it USB and not UPB?
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USB3 is not really serial - should it not be UPB
- Thread starter Rouxenator
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boobza
Honorary Master
That's not how you define parallel and serial communication. It's still serial.
Space_Chief
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You can connect your PC's USB connector to a hub which connects to a monitor (built in hub) which connects to a keyboard which can connect to a mouse. So devices are connected in series.
Lol. Series has nothing to do with serial.
No.
USB3 has a physically separate channel to carry USB3 data. The USB2 & USB3 operate independently from each other.
USB2 utilises 2-wires (single path) for data transmission which means you can only send data or receive data at any one point in time, you cannot send and receive at the same time, half-duplex.
USB3 has 4-wires (double path) (it does not use the 2 wires reserved for USB2) which allows it to send & receive data simultaneously, full-duplex.
It's pure serial, there is nothing parallel about it.
CataclysmZA
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Adding onto what ponder said, how serial and parallel connections work with the data is very different and isn't always related to the physical connection in use. In the end, both standards organise data into the same block, its just the way in which they send it that differs. If you'd like someone to explain in more detail how the parallel and serial standards differ, say so. I think I have a good explanation I wrote a while ago on another forum that would help.
Actually, that's not series, that's daisy-chaining. A single USB port can serve up to 127 devices on one port, but you typically run into bandwidth issues if you tried to use three or more of those devices at the same time.
Which is why I'd guess if you had to do a complex movement with the mouse by clicking and dragging something, while pressing five keys or using a macro on the keyboard while copying data from a USB flash drive plugged into your monitor, with everything using a single cable to a hub which connects to your PC, one of your devices would run into latency issues; another one would have to re-send its data payload and the third might show an error that it tried to draw too much power from the USB host port. This is all theoretical, but I've seen it happen before.
This is why I always re-arranged my customer's gadgets and gizmos connected to USB ports when helping set up their desktop or fix some other issue. Its also why my USB hub has a small memory buffer - I can copy stuff from one drive to the other on the hub and it runs at full speed without going through my already-loaded host controller.
bekdik
Honorary Master
Parallel is where all bits in a word of data are transmitted at the same time - the data bus width is the same width as the number of bits in the word.
Serial is where bits are transmitted one after another along a 1-bit wide data bus.
Serial is where bits are transmitted one after another along a 1-bit wide data bus.
Rouxenator
Dank meme lord
Cool. Makes sense now. So USB3 is actually 3 serial (1 bit wide) connections at the same time.
Parallel is where more than one bit is transmitted at a time, like the 4bit nibble on an old LPT port.
Parallel is where more than one bit is transmitted at a time, like the 4bit nibble on an old LPT port.
No. USB3 does not transmit/receive on the USB2 wires/pins.
Rouxenator
Dank meme lord
OK, full duplex serial it is.
Space_Chief
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In this case I guess it does not. But serial and in series are synonymous in general terms.
d0b33
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Lol Epic Fail is Epic... Developers these days....
Rouxenator
Dank meme lord
Yeah. We are pretty stupid at times.
No. Memory buffer is for different purpose. It is needed to accomodate devices with different speed and for transaction protocol operation.
I think you have mistaken USB with Firewire. USB is strictly host-target type of protocol, there is no possible to transfer data directly between two targets. All data is transfered from target-1 (initiated by host) to the host, and then from the host to target-2. There is only one host on the bus and target cannot become host dynamically. This is the same when two targets are physically connected to the same hub, as logical protocol matters.
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That is correct. I should have elaborated. The serial part applies wrt how the bits are moved back & forth. You were describing daisy chaining while the terminology refers to the movement of the bits.
Besides, USB has nothing to do with daisy chaining.