The Complete pinouts guide to Parallel-Serial Port, Network and Monitor Cables
Everything for DCC (Direct Cable Connection of Win95/98), Normal and Null Modem Cables, etc.
Guide compiled/collected/prepared/experimented by Mahendra from India

UNIVERSAL SERIAL BUS ( USB ) FUNDAMENTALS

The weirdo trident symbol above is the USB standardisation mark and found on all USB devices. Thousands of new USB compliant devices are coming into market ranging from Mouse, Keyboard, Scanner, Printers, Modem, Video Capture Devices, Gaming Consoles...the list is limitless.  I am not the technical / electronics engineer so I will not give in-depth details of this port but I will try my best to explain in simple language about the fundamentals of the USB as I learned.  I do not have any arguments with different opinions on this subject as the information may not be completely reliable on this page.  :-)

So let's go to understand what USB is?  http://www.usb.org/ is the best official place for technical info on USB.  Dear experts! Immediately go to this site and don't read further on this page. Novice users may stay on and keep reading.

USB:  A dream come true. Everyone wanted one IRQ and hundred peripherals

The restrictions of limited number of IRQ in one computer is over now.  Nowadays all motherboards have the USB ports for high-speed (1.5MBytes/sec to 12MBytes/sec) input and output of data to and from the computer.   New motherboards generally come with TWO built-in ports but they use single IRQ channel and single IO memory address.  On single IRQ channel we can use more than 112 USB devices on one computer using USB hubs or USB extension boxes.

There are two types of USB sockets. Type A and Type B.

Generally the USB sockets are given on CPU with USB-Type-A 
And the USB socket on the peripherals such as Scanner/printers etc are of USB Type B

The pinout description and the closeup shot of USB port on CPU Cabinet is given below. Notice the USB logo at top of it. 

USB Socket and Pinouts on Motherboard

Pin No. Name  Description
1 VCC  +5voltage  (max. 500mAmp)
2 D- Data - (Input to computer)
3 D+ Data + (Output from computer)
4 GND Ground for voltage

The port on motherboard gives the 5volt Output (500mAmp) to power the low voltage peripherals which can be used with computer without extra power supply like USB modems or Floppy Drives.  For my sony vaio laptop, I have an external Floppy Drive and CDROM drive which work only on USB ports and not the extra voltage power.  That's cool.  To know more on USB keep asking those cool silly questions so that I can put them in FAQ for everything else there are following links are enough.

GREAT LINKS ON USB
1. http://www.usb.org
2. http://www.everythingusb.com/usb1.1/ 
PICTURES OF COOL USB PRODUCTS
USB External Floppy Drive without power supply (Great for LAPTOP) I have one!

FAQ:  INDEX OF QUESTIONS
1. Any pinout of USB cable to connect two computers directly on USB?
2. What is the general speed of USB ? How do we compare it with other peripherals?
3. How does the standard USB cable look like?

FREQUENTLY GIVEN ANSWERS
1.  Any pinout of USB cable to connect two computers directly on USB?
Ans:  NO! It isNOT possible to connect two computers thru USB ports DIRECTLY.  There are some proprietary Cables available in market in less than 60$ which have a built-in electronic circuit with a special software to be installed on both machines. In fact, I am using one such cable to transfer files from my laptop to desktop at high speed, at 12Mbytes to 16MBytes per second, that's great speed. WARNING: Do not make USB cable on your own as USB ports do have 5volt DC current as output which can damage both motherboards.
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2.  What is the general speed of USB ? How do we compare it with other peripherals?
Ans:  The speed depends on the devices designed to communicate with USB controller on motherboard.  There are highspeed devices which can transfer data at 12Mbytes per second in one-way stream, and the low speed devices generally get peak speed of 1.5Mbytes per second. The latest USB controller version is USB 2.0. which can give peak speed above 12Mbytes per second. But wait ....the more and more research in USB field is going on and there is now new version coming up with 480Mbytes in very near future.
The comparison of USB with other IO ports can be verified as follows.
Serial Port 115kbits/s (0.115Mbits/s)
Standard Parallel Port (SPP) 115kBYTES/s (0.115MBYTES/s)
ECP/EPP parallel port: 3MBYTES/s
USB 12Mbits/s (1.5MBYTES/s)
USB 2.0 12MBytes/s
IDE  3.3 to 16.7MBYTES/s
UltraIDE 33MBYTES/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
Wide Ultra SCSI (Fast Wide 20) 40MBYTES/s
Ultra2 SCSI 40MBYTES/s
IEEE-1394 (FireWire) 100-400Mbits/s (12.5 to 50MBYTES/s)
Wide Ultra2 SCSI 80MBYTES/s
Ultra3 SCSI 80MBYTES/s
Wide Ultra3 SCSI 160MBYTES/s
FC-AL Fiber Channel 100-400MBYTES/s

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3.  How does the standard USB cable look like?
Ans:  The standard USB cable comes with USB-TYPE-A pin at one end which is connected at motherboard. At other end USB-TYPE-B pin is found which is little smaller and square and connected to the external USB peripherals such as USB modems, Scanners, Printers and thousands of USB devices. Following diagram shows the standard USB cable.

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Please read the website carefully and only if you have something extra to ask then email me with your requests, changes, questions, corrections at
pinout@indiacam.net  Thanks for visiting.