User manual EPSON LQ-2500

[. . . ] FCC COMPLIANCE STATEMENT FOR AMERICAN USERS This equipment generates and uses radio frequency energy and if not installed and used properly, that is, in strict accordance with the manufacturers instructions. may cause interference to radio and television reception. It has been type tested and found to comply with the limits for a Class B computing device in accordance with the specifications in Subpart J of part 15 of FCC Rules, which are designed to provide reasonable protection against such interference in a residential installation. However, there IS no guarantee that interference will not occur in a particular installation. [. . . ] Because the dots overlap each other both horizontally and vertically in the Letter Quality mode, it is difficult to see individual dots. Instead, the letters and symbols seem to be made of unbroken lines. In order for the dots to overlap vertically the pins are arranged on the print head in more than one column. The intelligence of the printer handles the timing of pin firings so that the effect is that of 24 pins arranged in a single vertical column. 6-2 Graphics and Userdefined Characters Dot patterns The LQ-2500 prints graphics the same way that pictures in newspapers and magazines are printed. If you look closely at a newspaper photograph, you can see that it is made up of many small dots. The LQ also forms its images with patterns of dots, as many as 360 dot positions per inch horizontally and 180 dots vertically The images printed by the LQ can, therefore, be as finely detailed as the one on the first page of this chapter. Eight-pin graphics The LQ has an eight-pin graphics mode with six densities, so that it is compatible with the many programs written for printers such as the Epson FX and RX series. Although this mode uses only one third of the LQ's pins, it produces good quality graphics and allows you to use the many programs written for eight-pin graphics. Twenty-four-pin graphics The 24-pin graphics mode takes full advantage of the LQ's print head. It has five densities, but for simplicity this explanation covers only triple-density Triple-density prints up to 180 dots per inch horizontally As the print head moves across the paper, every 1/180th of an inch it must receive instructions about which of its 24 pins to fire. At each position it can fire any number of pins from none to 24. This means that the printer must receive 24 bits of information for each column it prints. Since the LQ uses eight-bit bytes of information in its communication with a computer, it needs three bytes of information for each position. Pin labels The graphics mode requires a method to tell the printer which pins to fire in each column. The software must send codes for the dot patterns; one number is needed for each column in a line. For each of those columns the print head prints the pattern of dots you have specified. There are 256 possible combinations of eight pins, so a single number in the range O-255 can be used to specify which of the patterns you want. In this system, one number is assigned to each pin as in Figure 6-1, on the following page. Graphics and User- defined Characters 6-3 To fire any one pin, you send its number. To fire more than one pin at the same time, add up the numbers of the pins and send the sum to the printer. With these labels for the pins, you fire the top pin by sending 128. If you want to fire the top and bottom pins together, add 128 and 1, then send 129. By adding the appropriate label numbers together, you can fire any combination of pins. Figure 62 shows three examples of how to calculate the number that will fire a particular pattern of pins. With this numbering system, any combination of the eight pins adds up to a decimal number between 0 and 255, and no numbers are duplicated. Since there are 24 pins in each column, you must make a calculation for each of the three sections in each column. [. . . ] For definitions of terms, see the Glossary. A American Standard Code for Information Interchange, 4-2 - 3 Application programs, 4-1 - 12 setting up, 4-1 - 4 ASCII. 4-2 - 3 chart, B-1 -2 Auto line feed, 2-15 Automatic sheet feeder, 3-1 B Bail. paper, 1-2, 1-1 2 BASIC, 4-11 - 12 Baud rate, 2-14 Beeper. F-1-2, G-1 Buttons 1-6 - 9 SeiecType, 2-1 - 2 Buzzer. [. . . ]