english for user computers - tiếng anh cho người sử dụng vi tính: phần 3

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english for user computers - tiếng anh cho người sử dụng vi tính: phần 3 421 Analog transmission The older telephone systems function on the basis of analog signals representing voice modulation patterns which are represented by variations in wave forms.When using telephone lines for transmitting data by terminal to a computer, the digital signals from the terminal need to be converted to analog signals by an acoustic coupler or modem prior to transmission. A modem is a device which serves a dual purpose because it acts as a MOdulator (digital to analog) and DEModulator (analog to digital), hence the name MODEM. An analog communication system requires a modem at either end of the communication line. When the signals are received by the distant computer, the signals are reconverted to digital form prior to being input for processing. Digital transmission Analog transmission has been in use for many years as the basis of telephone technology and is very effective for this purpose, but it is not so suitable for high-speed transmission of information. Digital transmission consists of electrical pulses representing data in binary c6de as a series of on/off pulses. A number of different codes exist, som f of which are based on a 6-, 7-, or 8-bit structure. ASCII is a 7-bit code and EBCDIC is an 8-bit code. The codes represent characters, transmission control signals, information separators, and device control. Digital technology has a number of advantages compared to analog, including higher transmission speed, lower incidence of errors, and the facility for mixing data consisting of voice, image, and text on the same circuit. It is for this reason that data transmissions will be increasingly digital in the future. A network structure known as integrated Services Digital Network (ISDN) facilitates these aspects. 422 New word rating vi#c ddnh gid, x#p hqng download tdi xu6ng, tdi v i It all com es down to sth. Vdh d i chi Id do .... individual needs and preferences nhu cdu vd sd thick cd nhdn fiercely dc li 423 Computer software Phần mềm máy tỉnh Catherine Bull investigates This w eek : software S oftw are technology is getting m o re com plicated. D evelopers have to cut through a jungle of co m p u ter languages, o p e ra tin g environm ents, an d shifting stan d ard s to choose how they'll c r e a te th e ir softw are. It's not an easy job. S oftw are p u rch asers will have to Kve with th e results for y ears to com e. W hich advances in softw are technology will prevail? W hich ones will be just a flash in th e pan? I chose four well-known softw are developers a n d asked each to talk about c u rre n t and fu tu re tre n d s in so ftw are technology. T h eir com m ents rev eal som e com m on and diverse them es. I began by asking them if they thought th at softw are p u rch asers a re getting w hat they need? W hat should developers be doing differently to give p u rch asers a b e tte r product ? M ary Evans 'In general, I think people are getting what they want - there are a lot of creative things being done with paint software, word processing, DTP (desktop publishing) systems, and the like. Do users want more? Of course! Users will always want more. The computer is an incredibly powerful tool and any software that makes it easier, faster, more creative, or more cost-effective will inevitably be in demand. But I'm generally optimistic about the way things are going at the moment. I think most of the major software manufacturers are able to read the market quite well.' G e rry H a rp e r 'I'm afraid I completely disagree with Mary. I just don't think that software purchasers are getting the technical support they need. While the products are getting more and more complex, and more and more expensive, it seems that support is starting to be thought of as an additional business opportunity. More generally. I've thought for some time that applications are getting too big, and that they're trying to do too much. Yes they're versatile and powerful, but they're also often overwhelming. I think what we need are simple little programs that are easy to understand and use and that work together to accomplish more complex tasks.' 424 M a tt A n d rew s 'I really can't agreee with th a t T o im agine we can just go back to ’’simple little programs” just ignores the com plex needs of many of today's softw are users. No, I'm sure that you can't stop progress. Suppliers know what their custom ers want - they just can't supply it quickly enough. I've studied the m arket very closely, and I've found that purchasers' needs seem alw ays to exceed the capability of the available softw are by a constant tim e-fram e o f about six to twelve months.” Boh Bolton 'I think users are getting what they w ant, provided that their needs fit the off-the-shelf application. Specialized softw are is usually so specific that it should be written in-Iiouse for businesses. D evelopers should add features that the custom er needs, not what they think custom ers want. Some effort should be m ade to get feedback from the users before making an upgrade so that the proper features are added.' New word developer nhd phdt triin phdn m im prevail chiim Uu t h i a flash in the pan thdnh cdng nhdt thdi current and future trends cdc xu hudng hi$n tqi vd tucrng lai reveal tiit / ...