Understanding USB 2.0

I posted this sometime ago (Oct 2003) on a local (Singapore)

forums
:

Can’t these people just come out with easier to understand standards. OK, i
gotten me a Sony DSC-V1, it has a sticker that say:

Hi Speed USB, that is what speed i asked myself? USB not one speed only?

After searching high and low, i remember coming across some article on this in
PC Authority Oct
2003 Issue 71, there it is, right beside me now, pg 25.

Basically USB Standards:
Low Speed: 1.5Mb/s
Full Speed: 12Mb/s
Hi-Speed: 480Mb/s

So, be careful when you see labels (if any) for USB 2.0 products, not all USB
2.0 products are 480Mb/s.


Here’s the little sticker
that got me thinking on my camera.

See also http://www.usb.org/home So
comparing to other devices:

Taken from
http://www.usb.org/faq/ans2#q1

serial port: 115kbits/s (.115Mbits/s)
standard parallel port: 115kBYTES/s (.115MBYTES/s)
Original USB: 12Mbits/s (1.5MBYTES/s)
ECP/EPP parallel port: 3MBYTES/s
IDE: 3.3-16.7MBYTES/s
SCSI-1: 5MBYTES/s
SCSI-2 (Fast SCSI, Fast Narrow SCSI): 10MBYTES/s
Fast Wide SCSI (Wide SCSI): 20MBYTES/s
Ultra SCSI (SCSI-3, Fast-20, Ultra Narrow): 20MBYTES/s
UltraIDE: 33MBYTES/s
Wide Ultra SCSI (Fast Wide 20): 40MBYTES/s
Ultra2 SCSI: 40MBYTES/s
IEEE-1394: 100-400Mbits/s (12.5–50MBYTES/s)
Hi-Speed USB: 480Mbits/s
Wide Ultra2 SCSI: 80MBYTES/s
Ultra3 SCSI: 80MBYTES/s
Wide Ultra3 SCSI: 160MBYTES/s
FC-AL Fiber Channel: 100-400MBYTES/s
The fastest connection commonly found on PCs is UltraIDE, which is used for hard
drives and CD-ROMs.

Since we’re on this topic, there’s also the USB on the go logo now but as of
today, I’ve yet to seen it used a popular-ly as USB2.0 logos. Read about it @

http://www.usb.org/developers/onthego/

Basically it is:

"USB On-The-Go (OTG) allows two USB devices to talk to each other without
requiring the services of a personal computer. Although OTG appears to add "peer
to peer" connections to USB, it does not. Instead, USB OTG retains the standard
USB host/peripheral model, where a single host talks to USB peripherals. OTG
introduces the dual-role device (DRD), capable of functioning as either host or
peripheral. Part of the magic of OTG is that a host and peripheral can exchange
roles if necessary.
" – Source:

http://www.maxim-ic.com/appnotes.cfm/appnote_number/1822

Now,s just when you think you know USB, you get a whole chunk of it to
digest, blame it on my now-not-so-new camera. Enjoy!

 

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