CompTIA A_ Certification All-In-One Exam Guide, Seventh Edition - Michael Meyers [389]
A laser printer uses a chip called the raster image processor (RIP) to translate the raster image into commands to the laser. The RIP takes the digital information about fonts and graphics and converts it to a rasterized image made up of dots that can then be printed. An inkjet printer also has a RIP, but it’s part of the software driver instead of onboard hardware circuitry. The RIP needs memory (RAM) to store the data that it must process. A laser printer must have enough memory to process an entire page. Some images that require high resolutions require more memory. Insufficient memory to process the image will usually be indicated by a memory overflow (“MEM OVERFLOW”) error. If you get a memory overflow error, try reducing the resolution, printing smaller graphics, or turning off RET (see the following section for the last option). Of course, the best solution to a memory overflow error is simply to add more RAM to the laser printer.
Do not assume that every error with the word memory in it can be fixed simply by adding more RAM to the printer. Just as adding more RAM chips will not solve every conventional PC memory problem, adding more RAM will not solve every laser printer memory problem. The message “21 ERROR” on an HP LaserJet, for example, indicates that “the printer is unable to process very complex data fast enough for the print engine.” This means that the data is simply too complex for the RIP to handle. Adding more memory would not solve this problem; it would only make your wallet lighter. The only answer in this case is to reduce the complexity of the page image (that is, fewer fonts, less formatting, reduced graphics resolution, and so on).
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NOTE Inkjet printers use RIPs as well, but they’re written into the device drivers instead of the onboard programming. You can also buy third-party RIPs that can improve the image quality of your printouts; for an example, see www.colorbytesoftware.com.
Resolution
Laser printers can print at different resolutions, just as monitors can display different resolutions. The maximum resolution that a laser printer can handle is determined by its physical characteristics. Laser printer resolution is expressed in dots per inch (dpi). Common resolutions are 600 × 600 dpi or 1200 × 1200 dpi. The first number, the horizontal resolution, is determined by how fine a focus can be achieved by the laser. The second number is determined by the smallest increment by which the drum can be turned. Higher resolutions produce higher quality output, but keep in mind that higher resolutions also require more memory. In some instances, complex images can be printed only at lower resolutions because of their high-memory demands. Even printing at 300 dpi, laser printers produce far better quality than dot-matrix printers because of resolution enhancement technology (RET).
RET enables the printer to insert smaller dots among the characters, smoothing out the jagged curves that are typical of printers that do not use RET (Figure 22-16). Using RET enables laser printers to output high-quality print jobs, but it also requires a portion of the printer’s RAM. If you get a MEM OVERFLOW error, sometimes disabling RET will free up enough memory to complete the print job.
Figure 22-16 RET fills in gaps with smaller dots to smooth out jagged characters.
Installing a Printer in Windows
You need to take a moment to understand how Windows handles printing, and then you’ll see how to install, configure, and troubleshoot printers in these operating systems.
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EXAM TIP The CompTIA A+ exams test you on installing and troubleshooting printers, so read these sections carefully!
To Windows 2000, XP, and Vista/7, a printer