Star Micronics NX-10 user manual 121

121

ng-pin graphics mode

In the early part of this chapter, we said that the bottom pin of the print head is not normally used in the graphics modes. That’s because most computers communicate with parallel-type peripheral devices using eight data lines. When the peripheral 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? Well, for such graphics-intensive applications as screen dumps, printing 9 pins at a time can

speed up the process considerably. For this purpose, your printer has a special g-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 7-3.

128
64
32
16	First	byte
8
4
2
1
128		Second byte

(only the top bit is used)

Figure 7-3. Your printer takes 2 bytes to fire all 9 pins in case of the g-pin graphics mode.

In addition, you can select the print density by the value of nO. When nU 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 signifi- cant 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.