The display

Chapter The display

Teach Yourself Electricity and Electronics Third Edition Book
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Teach Yourself Electricity and Electronics Third Edition Book

  • “chip.” Other factors, such as microprocessor speed, have a practical effect on theusable memory capacity. A gigantic memory will not be of much use if the micro-processor is slow. Nor will a fast microprocessor be of practical value if the memorycapacity is too small for applications that demand high speed.The amount of memory you need depends on the applications you intend to run onyour computer. Most software packages will tell you how much memory you need.They’ll often quote two specifications: a minimum memory requirement and a figure foroptimum performance (approximately twice the minimum requirement). If possible,you should equip your computer with enough memory for optimum performance. Thisyear’s optimum machine is next year’s minimal one when it comes to popular software.If your computer lacks the memory to run a given application, you can usually addmore. But this can only be done up to a certain point. Eventually, your microprocessorwill no longer be able to run contemporary software at reasonable speed, no matter howmuch memory you have. When buying a new computer, it’s not a bad idea to err on theside of “too much” memory, rather than risk running short. How much memory do youthink your machine will require to run two or three of your favorite applications at thesame time? Double or triple it, and you will come close to the amount you are likely toneed for the next two or three years, until you are overcome by the urge to buy a newcomputer again. And you will get the urge. Computers can be downright seductive, es-pecially to people who have gotten this far in this book.Memory volatilityIn most computers, the memory is volatile. This means that it requires a source of powerto be maintained. If you switch the computer off, or if there’s a power failure, you’ll loseall the data in the memory. This problem can be avoided if the memory chips are suppliedwith power continuously. Some machines have rechargeable memory backup batteriesthat keep memory data intact for short periods if there is a power failure.In contrast to memory, the data on magnetic disks, or on optical media, will stay putwhen the power is removed. When you’re working on a file, it is wise to store the fileevery few minutes on the hard drive and/or diskette. That way, in the rare event a powerfailure does occur, you won’t lose much work.The displayThe visual interface between you and your computer is known as the display. Indesktop computers, an external display is often called a monitor. A cathode-ray-tube (CRT) monitor resembles a television set without the tuning or volume con-trols. A liquid-crystal-display (LCD) is lightweight and thin. This type of display isused in notebook and portable computers. It has become increasingly popular fordesktop computers because the technology has improved and has become some-what less expensive.Showing detailThe image resolution of a computer display is important. This is the extent towhich it can show detail: the better the resolution, the sharper the image. Resolutioncan be specified in terms of dot size or dot pitch. This is the diameter, in millimetersThe display631