Epson LQ-800 Figure 6-1. Pin numbering system, Figure 6-2.Calculations for pin patterns

128

64

32

16

8

4

2

1

Figure 6-1.Pin numbering system

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. To fire the bottom pin, you send 1. If you want to fire only the top and bottom pins, you simply add 128 and 1, then send 129.

By adding the appropriate label numbers together, you can fire any combination of pins. Figure 6-2shows three examples of how to calculate the number that will fire a particular pattern of pins.

Figure 6-2. Calculations for pin patterns

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. As you can see, this method of planning and printing dot graphics requires considerable calculation. Because triple-density uses 180 columns per inch, printing

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