Cases where an inventor creates a complex electrical device from scratch, relying solely on his own research, are extremely rare. As a rule, certain devices are born at the junction of several technologies and standards created by different people at different times. For example, take a banal flash drive. This is a portable storage device based on non-volatile NAND memory and equipped with a built-in USB port that is used to connect the drive to a client device. Thus, in order to understand how such a device could, in principle, appear on the market, it is necessary to trace the history of the invention of not only the memory chips themselves, but also the corresponding interface, without which the flash drives familiar to us would simply not exist. Let's try to do this.
Semiconductor memory devices that support the erasure of recorded data appeared almost half a century ago: the first EPROM was created by Israeli engineer Dov Froman back in 1971.
Dov Froman, EPROM developer
ROMs, innovative for their time, were quite successfully used during the production of microcontrollers (for example, Intel 8048 or Freescale 68HC11), but turned out to be decisively unsuitable for creating portable drives. The main problem with EPROM was the too complex procedure for erasing information: for this, the integrated circuit had to be irradiated in the ultraviolet spectrum. The way it worked was that the photons of the UV radiation gave the excess electrons enough energy to dissipate the charge on the floating gate.
The EPROM chips were provided with special windows for erasing data, closed by quartz plates.
This added two significant inconveniences. First, it was possible to erase data on such a chip in adequate time only with the help of a sufficiently powerful mercury lamp, and even in this case, the process took several minutes. For comparison: a conventional fluorescent lamp would delete information within a few years, and if you leave such a chip in direct sunlight, then it would take weeks to completely clean it. Secondly, even if this process could be somehow optimized, the selective deletion of a particular file was still impossible: the information on the EPROM was erased entirely.
These problems were solved in the next generation of chips. In 1977, Eli Harari (by the way, who later founded SanDisk, one of the world's largest manufacturers of data carriers based on flash memory), using field emission technology, created the first prototype of EEPROM - ROM, in which erasing data, like programming, carried out purely electrically.
Eli Harari, founder of SanDisk, holding one of the first SD cards
The principle of operation of EEPROM was almost identical to that of modern NAND memory: a floating gate was used as a charge carrier, and the transfer of electrons through dielectric layers was carried out due to the tunnel effect. The very organization of the memory cells was a two-dimensional array, which already made it possible to write and delete data by address. In addition, EEPROM had a very good margin of safety: each cell could be overwritten up to 1 million times.
But here, too, things were by no means so rosy. To be able to erase data electrically, an additional transistor had to be introduced into each memory cell, which controls the process of writing and erasing. Now there were 3 wires per array element (1 column wire and 2 row wires), which made the layout of the matrix components more complicated and there were serious problems with scaling. So, the creation of miniature and capacious devices was out of the question.
Since a ready-made semiconductor ROM already existed, further scientific research continued with an eye to the creation of chips that could provide denser data storage. And those were crowned with success in 1984, when Fujio Masuoka, who worked at Toshiba Corporation, presented a prototype of non-volatile flash memory at the international conference International Electron Devices Meeting, held within the walls of the Institute of Electrical and Electronics Engineers (IEEE).
Fujio Masuoka, father of flash memory
By the way, the name itself was not invented by Fujio at all, but by one of his colleagues, Shoji Ariizumi, to whom the process of erasing data reminded him of a shining flash of lightning (from the English “flash” - “flash”). Unlike EEPROM, flash memory was based on MOSFETs with an additional floating gate located between the p-layer and the control gate, which made it possible to eliminate unnecessary elements and create truly miniaturized chips.
The first commercial samples of flash memory were Intel chips made using NOR (Not-Or) technology, the production of which was launched in 1988. As in the case of EEPROM, their matrices were a two-dimensional array, in which each memory cell was at the intersection of a row and a column (the corresponding conductors were connected to different gates of the transistor, and the source was connected to a common substrate). However, already in 1989, Toshiba introduced its own version of flash memory, called NAND. The array had a similar structure, but in each of its nodes, instead of one cell, there were now several consecutive ones. In addition, two MOS transistors were used in each line: a control transistor located between the bit line and a column of cells, and a ground transistor.
A higher packing density helped to increase the chip capacity, but at the same time, the read / write algorithm became more complicated, which could not but affect the information transfer rate. For this reason, the new architecture was never able to completely replace NOR, which was used in the creation of embedded ROMs. At the same time, it was NAND that turned out to be ideal for the production of portable data storage devices - SD cards and, of course, flash drives.
By the way, the appearance of the latter became possible only in 2000, when the cost of flash memory dropped sufficiently and the release of such devices for the retail market could pay off. The world's first USB drive was the brainchild of the Israeli company M-Systems: a compact DiskOnKey flash drive (which can be translated as "disk-on-keychain", since a metal ring was provided on the device case that allowed you to carry a USB flash drive along with a bunch of keys) was developed by engineers Amir Banom, Dov Moran and Oran Ogdan. For a miniature device capable of holding 8 MB of information and replacing the heels of 3,5-inch floppy disks, at that time they asked for $50.
DiskOnKey - the world's first flash drive from the Israeli company M-Systems
An interesting fact: in the United States, DiskOnKey had an official publisher, which was IBM. The "localized" flash drives were no different from the original ones, with the exception of the logo on the front, which is why many mistakenly attribute the creation of the first USB drive to an American corporation.
DiskOnKey, IBM Edition
Following the original model, just a couple of months later, more capacious modifications of DiskOnKey for 16 and 32 MB saw the light, for which they were already asking for $100 and $150, respectively. Despite the high cost, the combination of compact size, capacity and high read / write speed (which turned out to be about 10 times faster than standard floppy disks) appealed to many buyers. And from that moment on, flash drives began their triumphal march across the planet.
One man in the field: the battle for USB
However, a flash drive would not have been a flash drive if the Universal Serial Bus specification had not appeared five years earlier - this is how the abbreviation USB that we are used to stands for. And the history of the emergence of this standard can be called almost more interesting than the invention of flash memory itself.
As a rule, new interfaces and standards in IT are the result of close cooperation between large enterprises, often even competing with each other, but forced to join forces to create a unified solution that would greatly simplify the development of new products. This happened, for example, with SD memory cards: the first version of the Secure Digital Memory Card was created in 1999 with the participation of SanDisk, Toshiba and Panasonic, and the new standard was so successful that it was awarded the industry title just a year later. Today, the SD Card Association has over 1000 member companies whose engineers are developing new and developing existing specifications that describe various parameters of flash cards.
And at first glance, the history of USB is completely identical to what happened with the Secure Digital standard. To make personal computers more friendly to the average user, hardware manufacturers needed, among other things, a universal interface for working with peripherals that supports hot plugging and does not require additional configuration. In addition, the creation of a unified standard would make it possible to get rid of the "zoo" of ports (COM, LPT, PS / 2, MIDI-port, RS-232, etc.), which in the future would help to significantly simplify and reduce the cost of developing new equipment, as well as the introduction of support for certain devices.
Against the background of these prerequisites, a number of companies developing computer components, peripherals and software, the largest of which were Intel, Microsoft, Philips and US Robotics, united in an attempt to find the very common denominator that would suit all existing players, which eventually became USB . The popularization of the new standard was largely facilitated by Microsoft, which added support for the interface back in Windows 95 (the corresponding patch was part of Service Release 2), and then introduced the necessary driver into the release version of Windows 98. At the same time, on the iron front, help came from nowhere waited: in 1998, the iMac G3 saw the light - the first all-in-one computer from Apple, in which only USB ports were used to connect input devices and other peripherals (with the exception of a microphone and headphones). In many ways, this 180-degree turn (after all, at that time Apple was betting on FireWire) was due to the return of Steve Jobs to the post of CEO of the company, which took place a year earlier.
The original iMac G3 is the first "USB computer"
In fact, the birth of the universal serial bus was much more painful, and the emergence of USB itself is largely the merit of not mega-corporations and not even one research department operating as part of a particular company, but of a very specific person - an Intel engineer of Indian origin named Ajay Bhatt.
Ajay Bhatt, chief ideologue and creator of the USB interface
Back in 1992, Ajay thought that "personal computer" did not really justify its own name. Even such a seemingly simple task as connecting a printer and printing a document required a certain qualification from the user (although, it would seem, why would an office worker who is required to create a report or statement need to understand sophisticated technologies?) Or forced to turn to specialized specialists . And if everything is left as it is, the PC will never become a mass product, which means that going beyond the figure of 10 million users worldwide is not worth even dreaming of.
Both Intel and Microsoft understood the need for some kind of standardization at that time. In particular, research in this area led to the emergence of the PCI bus and the Plug & Play concept, which means that Bhatt's initiative, who decided to focus his efforts on finding a universal solution for connecting peripherals, should have been received positively. But that was not the case: Ajay's immediate supervisor, after listening to the engineer, said that this task was so difficult that it was not worth wasting time on it.
Then Ajay began to look for support in parallel groups and found one in the person of one of the distinguished Intel researchers (Intel Fellow) Fred Pollack, known at that time for his work as the lead engineer of the Intel iAPX 432 and the lead architect of the Intel i960, who gave the project a green light . However, this was only the beginning: the implementation of such a large-scale idea would have become impossible without the participation of other market players. From that moment on, the real "going through the throes" began, because Ajay had to not only convince the members of the Intel working groups that this idea was promising, but also enlist the support of other iron manufacturers.
It took almost a year and a half for numerous discussions, approvals and brainstorming. During this time, Ajay was joined by Bala Kadambi, who led the team responsible for the development of PCI and Plug & Play, and later became Intel's director of technology standards for I / O interfaces, and Jim Pappas, an expert in I / O systems. In the summer of 1994, we finally managed to form a working group and begin closer interaction with other companies.
Over the next year, Ajay and his team met with more than 50 firms, ranging from small, niche businesses to giants like Compaq, DEC, IBM, and NEC. The work was in full swing literally 24/7: from the early morning the trio went to numerous meetings, and at night they met at the nearest diner to discuss the plan of action for the next day.
Perhaps, to some, this style of work may seem like a waste of time. Nevertheless, all this paid off: as a result, several multifaceted teams were formed, which included engineers from IBM and Compaq specializing in the creation of computer components, people involved in the development of chips from Intel and NEC itself, programmers who worked on creating applications, drivers and operating systems (including from Microsoft), and many other specialists. It was the simultaneous work on several fronts that eventually helped create a truly flexible and universal standard.
Ajay Bhatt and Bala Kadambi at the European Inventor Prize
Although Ajay's team managed to brilliantly solve the problems of a political (by achieving the interaction of various companies, including direct competitors) and technical (gathering many experts in various fields under one roof), there was one more aspect that required close attention - the economic side of the issue. And here we had to make significant compromises. So, for example, it was the desire to reduce the cost of the wire that led to the fact that the USB Type-A familiar to us, which we use to this day, has become one-sided. Indeed, to create a truly universal cable, it would be necessary not only to change the design of the connector, making it symmetrical, but also to double the number of conductive cores, which would also double the cost of the wire. But now we have an ageless meme about the quantum nature of USB.
Other project participants also insisted on lowering the cost. Jim Pappas, in this regard, likes to recall a call from Microsoft's Betsy Tanner, who announced one day that, unfortunately, the company intends to stop using the USB interface in the production of computer mice. The thing is that the bandwidth of 5 Mbps (this is the data transfer rate that was originally planned) was unnecessarily high, and the engineers were afraid that they would not be able to meet the specifications for electromagnetic interference, which means that such a “turbo mouse” could interfere with the normal functioning both the PC itself and other peripheral devices.
To a reasonable argument about shielding, Betsy replied that the extra insulation would make the cable more expensive: 4 cents on top for every foot, or 24 cents on standard 1,8 meters (6 feet) wire, which makes the whole idea pointless. In addition, the mouse cable must remain flexible enough to allow free movement of the hand. To solve this problem, it was decided to add a division into high-speed (12 Mbps) and low-speed (1,5 Mbps) modes. A margin of 12 Mbps made it possible to use splitters and hubs to simultaneously connect multiple devices on one port, and 1,5 Mbps was optimal for connecting mice, keyboards and other similar devices to a PC.
Jim himself considers this story a stumbling block, which ultimately ensured the success of the entire project. Indeed, without the support of Microsoft, it would be much more difficult to promote a new standard on the market. In addition, the found compromise helped to make USB much cheaper, and therefore more attractive in the eyes of manufacturers of peripheral equipment.
What's in my name to you, or Crazy rebranding
And since today we are discussing USB drives, let's at the same time clarify the situation with the versions and speed characteristics of this standard. Everything here is not at all as simple as it might seem at first glance, because since 2013 the USB Implementers Forum has made every effort to completely confuse not only ordinary consumers, but also professionals from the IT world.
Previously, everything was quite simple and logical: we have a slow USB 2.0 with a maximum bandwidth of 480 Mbps (60 Mbps) and a 10 times faster USB 3.0, which has a data transfer limit of 5 Gbps ( 640 MB/s). Due to backwards compatibility, a USB 3.0 drive can be connected to a USB 2.0 port (or vice versa), however, the speed of reading and writing files will be limited to 60 MB / s, since a slower device will act as a “bottleneck”.
On July 31, 2013, USB-IF introduced a fair amount of confusion into this slender system: it was on this day that the adoption of a new specification, USB 3.1, was announced. And no, it’s not at all about fractional version numbering, which has happened before (although in fairness it’s worth noting that USB 1.1 was a modified version of 1.0, and not something qualitatively new), but that the USB Implementers Forum for some reason decided to rename the old standard. Watch your hands:
- USB 3.0 has become USB 3.1 Gen 1. This is a clean renaming: no improvements have been made, and the maximum speed has remained the same - 5 Gb / s and no more.
- USB 3.1 Gen 2 has become a truly new standard: switching to 128b / 132b encoding (previously used 8b / 10b) in full-duplex mode has doubled the interface bandwidth and achieved an impressive 10 Gb / s, or 1280 MB / s.
But this was not enough for the guys from USB-IF, so they decided to add a couple of alternative names: USB 3.1 Gen 1 became SuperSpeed, and USB 3.1 Gen 2 became SuperSpeed+. And just this step is quite justified: for a retail buyer, far from the world of computer technology, it is much easier to remember a catchy name than a sequence of letters and numbers. And here everything is intuitive: we have a "super-fast" interface, which, as the name implies, is very fast, and there is a "super-fast +" interface, which is even faster. But why at the same time it was necessary to carry out such a specific “rebranding” of generation indices is completely incomprehensible.
However, there is no limit to imperfection: on September 22, 2017, with the publication of the USB 3.2 standard, the situation worsened even more. Let's start with the good: the reversible USB Type-C connector, whose specifications were developed for the previous generation of the interface, allowed us to double the maximum bus throughput by using redundant pins as a separate data transfer channel. This is how USB 3.2 Gen 2 × 2 appeared (why it could not be called USB 3.2 Gen 3, again a mystery), operating at speeds up to 20 Gb / s (2560 MB / s), which, in particular, found application in the production of external solid-state drives (this is the port equipped with high-speed WD_BLACK P50, aimed at gamers).
And everything would be fine, but, in addition to the introduction of a new standard, the renaming of the previous ones was not long in coming: USB 3.1 Gen 1 turned into USB 3.2 Gen 1, and USB 3.1 Gen 2 into USB 3.2 Gen 2. Even marketing names have changed, moreover USB-IF moved away from the previously adopted concept of "intuitively clear and no numbers": instead of designating USB 3.2 Gen 2x2 as, for example, SuperSpeed++ or UltraSpeed, they decided to add a direct indication of the maximum data transfer rate:
- USB 3.2 Gen 1 became SuperSpeed USB 5Gbps,
- USB 3.2 Gen 2 - SuperSpeed USB 10Gbps,
- USB 3.2 Gen 2x2 - SuperSpeed USB 20Gbps.
And how to deal with the zoo of USB standards? To make your life easier, we have compiled a summary table-reminder, with the help of which it will not be difficult to compare different versions of interfaces.
Standard version
Marketing name
Speed, Gbps
USB 3.0
USB 3.1
USB 3.2
USB version 3.1
USB version 3.2
USB 3.0
USB 3.1 Gen 1
USB 3.2 Gen 1
SuperSpeed
SuperSpeed USB 5Gbps
5
-
USB 3.1 Gen 2
USB 3.2 Gen 2
SuperSpeed+
SuperSpeed USB 10Gbps
10
-
-
USB 3.2 Gen 2 × 2
-
SuperSpeed USB 20Gbps
20
Variety of USB drives using the example of SanDisk products
But let's return directly to the subject of today's discussion. Flash drives have become an integral part of our lives, having received many modifications, sometimes quite bizarre. For the most complete picture of the capabilities of today's USB flash drives, check out the SanDisk portfolio.
All current models of SanDisk flash drives support the USB 3.0 data transfer standard (aka USB 3.1 Gen 1, aka USB 3.2 Gen 1, aka SuperSpeed - almost like in the movie "Moscow Doesn't Believe in Tears"). Among them you can find both quite classic flash drives and more specialized devices. For example, if you're looking for a compact all-in-one drive, it makes sense to look into the SanDisk Ultra line.
SanDisk Ultra
The presence of six modifications of different capacities (from 16 to 512 GB) helps you choose the best option depending on your needs and not overpay for extra gigabytes. Data transfer speeds up to 130 MB / s allow you to quickly download even large files, and a convenient sliding case reliably protects the connector from damage.
For fans of elegant shapes, we recommend the SanDisk Ultra Flair and SanDisk Luxe USB Flash Drives.
SanDisk Ultra Flair
Technically, these flash drives are completely identical: both series are characterized by data transfer rates up to 150 MB / s, and each of them includes 6 models with capacities from 16 to 512 GB. The differences lie only in the design: Ultra Flair received an additional structural element made of durable plastic, while the body of the Luxe version is completely made of aluminum alloy.
SanDisk Luxe
In addition to the spectacular design and high data transfer speed, the listed drives have another very interesting feature: their USB connectors are a direct continuation of the monolithic case. This approach provides the highest level of flash drive security: it is simply impossible to accidentally break such a connector.
In addition to full-size drives, the SanDisk collection also includes plug-and-forget solutions. We are talking, of course, about the ultra-compact SanDisk Ultra Fit, whose dimensions are only 29,8 × 14,3 × 5,0 mm.
SanDisk UltraFit
This baby barely protrudes from the surface of the USB connector, making it ideal for expanding the storage of a client device, whether it be an ultrabook, car audio system, Smart TV, game console or single board computer.
The most interesting in the SanDisk collection are Dual Drive and iXpand USB drives. Both families, despite the design differences, are united by a single concept: these flash drives received two ports of different types, which allows them to be used to transfer data between a PC or laptop and mobile gadgets without additional cables and adapters.
Drives of the Dual Drive family are designed for use with smartphones and tablets running the Android operating system and supporting OTG technology. This includes three lines of flash drives.
The miniature SanDisk Dual Drive m3.0, in addition to USB Type-A, is equipped with a microUSB connector, which ensures compatibility with devices of yesteryear, as well as entry-level smartphones.
SanDisk Dual Drive m3.0
SanDisk Ultra Dual Type-C, as you might guess from the name, got a more modern two-way connector. The flash drive itself has become larger and more massive, but this case design provides better protection, and it has become much more difficult to lose the device.
SanDisk Ultra Dual Type-C
If you're looking for something a little more elegant, we recommend the SanDisk Ultra Dual Drive Go. These drives implement the same principle as the previously mentioned SanDisk Luxe: a full-size USB Type-A is part of the flash drive body, which prevents it from breaking even with careless handling. The USB Type-C connector, in turn, is well protected by a swivel cap, which also has an eyelet for a keychain. This arrangement made it possible to make the flash drive truly stylish, compact and reliable.
SanDisk Ultra Dual Drive Go
The iXpand series is completely similar to the Dual Drive, except for the fact that the USB Type-C has been replaced by Apple's proprietary Lightning connector. The most unusual device in the series can be called SanDisk iXpand: this flash drive has an original design in the form of a loop.
SanDisk iXpand
It looks spectacular, besides, you can put a strap through the resulting eyelet and wear the drive, for example, around your neck. Yes, and using such a flash drive with an iPhone is much more convenient than a traditional one: when connected, most of the body is behind the smartphone, resting on its back cover, which helps to minimize the likelihood of damage to the connector.
If such a design for one reason or another does not suit you, it makes sense to look towards the SanDisk iXpand Mini. Technically, we still have the same iXpand: the lineup also includes four drives of 32, 64, 128 or 256 GB, and the maximum data transfer rate reaches 90 MB / s, which is enough even to watch 4K video directly from a flash drive. The difference lies only in the design: the loop has disappeared, but a protective cap for the Lightning connector has appeared.
SanDisk iXpand Mini
The third member of the glorious family, SanDisk iXpand Go, is the twin brother of Dual Drive Go: their dimensions are almost identical, in addition, both drives received a swivel cap, albeit a slightly different design. This line includes 3 models: 64, 128 and 256 GB.
SanDisk iXpand Go
The list of products manufactured under the SanDisk brand is by no means limited to the listed USB drives. You can get acquainted with other devices of the famous brand at .
Source: habr.com