Star Micronics ND-10/15 user manual Printer needs 2 bytes to tire all 9 pins in the 9-pin

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is a printer, each data line corresponds to one pin on the print head. Thus each byte sent will fire up to eight pins.

But the printer has 9 pins available. So how do you fire the ninth pin with only 8 data lines? In fact, do you really want to bother with just one extra pin? For this purpose, your printer has a special 9-pin graphics mode (it won’t, however, work with 7-bit interface systems). In this mode the printer takes 2 bytes to fire all 9 pins as shown in Figure 7-8. For such

graphics-intensive applications as screen dumps, printing 9 pins at a time can speed up the process considerably.

0	128
L
	64
:	32
E	16	) First byte
0	8
	4
	2
:	I	!
0	128	Second byte

(only the top bit is used)

Figure 7-8.The printer needs 2 bytes to tire all 9 pins in the 9-pin

graphics mode.

In addition, you can select the print density by the value qf n0. When nO is 0 the normal density is selected, and when nO is 1 the double density is selected.

Since computers are faster than printers, there is no signif- icant time loss in printing a single line of graphics with 9 pins. You get 9 dots per line in about the same time as you get 8 dots in the other graphics modes.