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TMCNet:  Who invented the USB flash drive?

[February 09, 2013]

Who invented the USB flash drive?

(Flare (Pakistan) Via Acquire Media NewsEdge) The USB Flash Drive was introduced in 1998. The USB interfaced NAND memory was invented by Dov Moran. He worked for M-Systems, where the very first Flash Drive was manufactured.

Netac and Trek2000, Ltd. developed similar products about the same time. All three companies, MSystems, Netac and Trek2000, have very similar and hotly disputed patents.

The first Flash Drive was manufactured and distributed in Europe under the "disgo" brand name. It was only available in four sizes; 8MB, 16MB, 32MB, and 64MB. The first distributor in North America was IBM.

The history of flash drives is brief, but here's what we know so far. The birth of the flash drive is credited to Dr. Fujio Masuoka. He invented NOR and NAND Flash Memory while working for Toshiba. The release of the first removable drive was in 1984, using Masuoka's NOR Flash Memory. It was in 1984 when he invented NOR Flash Memory, which is the predecessor to NAND Flash Memory.

How USB works: Today, a PC user expects to be able to connect his or her system to a wide range of external devices: not just printers and modems, but scanners, video cameras, portable storage devices, PDAs and a host of other peripherals. But for a long time, anyone attempting to do so was hampered by a lack of suitable I/O ports.

Designed originally for printers and low speed modems, the PC’s serial and parallel ports leave a lot to be desired as general purpose interfaces. Their data transfer rate is low (maximum 115Kbit/sec for the serial port, up to 400KB/sec for a parallel interface) and each device requires its own hardware interrupt (IRQ) which limits the amount of expansion possible. Nor is there any hope of achieving plug and play operation with these interfaces, something that is essential if attaching peripherals to a PC is to be made something that can be accomplished by non-technical users.

The need for a medium-speed, inexpensive plug and play interface that can be used to attach a practically unlimited number of devices was eventually recognized, and the solution was the Universal Serial Bus (USB). Design aims: The USB was designed to allow large numbers (up to 127) of low and medium speed peripherals to be attached to a PC. With a top transfer rate of 12Mbit/sec USB was never intended to be an alternative to SCSI. But it is still much faster than the serial or parallel ports.

Particular attention was paid to the needs of audio and video devices, which it was envisaged would be increasingly important for the next generation of personal productivity applications. The design of the USB provides for this time-critical isochronous data to be delivered The need for a medium-speed, inexpensive plug and play interface that can be used to attach a practically unlimited number of devices that can be added and removed even while the system is running, avoiding the need to reboot the system to reconfigure it without delays that would adversely affect the quality of images and speech.

USB was designed to be plug and play. Devices can be added and removed even while the system is running, avoiding the need to reboot the system to reconfigure it. Technical issues like bus termination and the assignment of device identifiers are taken care of by the hardware and software architecture so these common sources of configuration error will not be a problem. Concerns for power conservation have been catered for by allowing devices to be suspended and resumed.

Typical USB devices are those requiring low and medium bandwidths. At the bottom end of the bandwidth range, USB could be used to connect a keyboard and mouse to a PC. At the top end, scanners, backup devices or cameras for video-conferencing applications could use USB, eliminating the need for proprietary interface boards with their associated installation and configuration problems.

The bus architecture, in which data for different devices travels across the same cable, also has the potential for simplifying connection requirements. For example, a mouse could plug into a keyboard, and a single cable would then link these with the PC. Although monitors would still need an analogue VGA cable, a separate USB link would allow the monitor to be adjusted from software on the PC instead of an on screen display. In the case of a multimedia monitor, audio data for built-in speakers and a microphone could also be sent over the same cable.

Physical layer: USB devices are connected together using an inexpensive white jacketed four wire cable with a characteristic impedance of 90 ohms. USB devices can be either self-powered (with their own independent power supply) or bus powered.

One of the pair of wires in the USB cable is used to carry 5V power: pin 1 carries the supply voltage of +5V, pin 4 is ground. There are two classes of bus-powered device. Low power devices may draw no more than 100mA of current, whilst high power devices can draw up to 500mA once configured.

The second pair of wires, D+ and Don pins two and three, is a twisted pair used to carry data. The data wires use differential signalling: both carry a signal with respect to ground, and a transition occurs when the two data lines reverse polarity with respect to one another. This gives better immunity to noise than the conventional single ended logic signal. n

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