PrefaceThe ARPANET – the Department of Defense network that is the ancestor of today’s Internet—was built in the late sixties using a proprietary protocol This first protocol proved to have shortcomings for linking with other networks， which led to the development of Transfer Control Protocol/Internet Protocol (TCP/IP) TCP/IP used 32-bit address These soon proved to be unwieldy for most users， even when expressed in the less daunting formant of four 8-bit decimal numbers， delimited by The obvious solution was a scheme for addressing computers by After all， people relate much better to names and find it much easier to remember the computer in the corner as “Frodo，” rather than “”The First Generation: Hot TablesThe desire to refer to machines by name instead of number led to the first IP address management scheme: the host The host table is a file that contains all the IP address in use on a network， along with their The host table provides a mapping from a host’s name to its IP address， as well as reverse mapping: Given a host’s IP address， the user can look up its For a host table to be most user useful， it must contain the names of all the hosts with which a given host might want to For the ARPANET， that mean that the host table had to contain the names and IP address of every host on the Such a file was maintained by the Network Information Center (NIC)， the central organization responsible for managing the ARPANET The file was called HOSTSTXT and was similar in format to the/etc/hosts file on UNIX Network administrators all over the network e-mailed host table changed to the NIC every time they added or deleted a host or changed a host’s IP The NIC made the changes to its master host table， which it made available via File Transfer Protocol (FTP) Administrators periodically downloaded the latest version of the host table to stay
这是《科学美国人》杂志上的《PLASTICS GET WIRED》Like many technological advances， the innovations in the field ofconducting polymers began by While attempting tomake an organic polymer called polyacetylene in the early1970s， Hideki Shirakawa of the Tokyo Institute of Technology mistakenlyadded 1，000 times more catalyst than the recipe called What he producedwas a lustrous， silvery film that resembled aluminum foil butstretched like Saran Wrap—something that sounds more like a new andimproved way to keep leftovers fresh than a potential breakthrough inmaterials The substance appeared so unusual that when Alan G MacDiarmidspied it， he wondered if it would be a candidate for his goal of making“synthetic metals”—nonmetallic substances that could transmit In 1977 Shirakawa joined MacDiarmid and Alan J Heeger in their laboratoryat the University of Pennsylvania to investigate this form of After mixing in some iodine， the group found that the material’sconductivity subsequently jumped by a factor of several Durable， cheap， manufacturable and flexible， conducting polymers inspiredvisions of a future of transparent circuits， artificial muscle and electronicdisplays that conveniently roll up under the Researchers haveauditioned various demonstration devices， including components thatcould be useful for new displays， such as plastic transistors and light-emittingdiodes (LEDs) Although such a future is about as dreamy as it gets，many investigators see broad marketing opportunities possible now—inantistatic coatings， electromagnetic shielding， lights for toys and microwaveovens， among Perhaps mundane， such applications are nonethelesspromising enough that universities are collaborating with corporations，and scientists have initiated start-Although the pace of technological innovation has been impressivelybrisk， whether the materials will have an effect on commerce remains Firms are unlikely to invest in new equipment if the devices performonly marginally better than existing Polymer-based batteries，for instance， have a longer shelf life than do conventional ones， but theyhave penetrated the market in only a limited Flat-panel displays andLEDs made of organic substances face entrenched competition from existinginorganic liquid crystals and Still， optimism pervades the Because plastic and electrical deviceshave become integral parts of the modern world， researchers are confidentthat at least some profitable uses will Conducting polymers constitutea radically novel market area， points out Ray H Baughman of Allied-Signal in Morristown， NJ， who predicts confidently， “Fortunes aregoing to be ”Polymers， the constituents of familiar plastic materials and syntheticfibers， are large organic molecules built out of smaller ones linked togetherin a long Generally， they are insulators， because their moleculeshave no free electrons for carrying To make these substances conductive，workers exploit a technique familiar to the semiconducting industry:doping， or adding atoms with interesting electronic Theadded atoms either give up some of their spare electrons to the polymerbonds or grab some electrons from the bonds (and thereby contribute positivecharges called holes) In either case， the chain becomes electrically Applying a voltage can then send electrons scampering over thelength of the 《MICROPROCESSORS IN 2020》Unlike many other technologies that fed our imaginationsand then faded away， the computer hastransformed our There can be little doubtthat it will continue to do so for many decades to Theengine driving this ongoing revolution is the microprocessor，the sliver of silicon that has led to countless inventions， suchas portable computers and fax machines， and has added intelligenceto modern automobiles and Astonishingly，the performance of microprocessors has improved25，000 times over since their invention only 27 years I have been asked to describe the microprocessor of Such predictions in my opinion tend to overstate the worthof radical， new computing Hence， I boldly predictthat changes will be evolutionary in nature， and not Even so， if the microprocessor continues to improveat its current rate， I cannot help but suggest that 25 yearsfrom now these chips will empower revolutionary software tocompute wonderful 《HOW THE SUPERTRANSISTORWORKS》Although it is rarely acknowledged，not one but two distinctelectronic revolutionswere set in motion by the invention ofthe transistor 50 years ago at Bell TelephoneL The better knownof the two has as its hallmark the trendtoward This revolutionwas fundamentally transformed in thelate 1950s， when Robert N Noyce andJack Kilby separately invented the integratedcircuit， in which multiple transistorsare fabricated within a single chipmade up of layers of a Years of this miniaturizationtrend have led to fingernail-size sliversof silicon containing millions of transistors，each measuring a few microns andconsuming perhaps a millionth of a wattin 如果需要更多跟我联系，我有pdf版的资料。
