Tally Genicom Matrix Printer manual Dot Graphics, 5Dot Column Coding

Dot Graphics

Dot graphics allows you to print individual dots at any position on the page and thus to print pictures as well as text. When you enter dot graphics, the printer defaults to a dot density of 72 dpi horizontally and vertically, and a line spacing of 12 lpi. Exiting from dot graphics returns the printer to its prior lpi setting. You can also choose a density of 144 dpih x 72 dpiv. The printer powers up in low density. The density remains as last set until it is changed, or until power is turned off.

Each byte of graphics data defines one column of dots that is six dots high. You can think of the least significant six bits in the byte as controlling the topmost six wires of the print head, with the first bit controlling the top wire and the sixth bit controlling the sixth wire down. If you wanted to fire all six wires, then you would send a byte with a decimal value of 63. Byte values of 0 through 31 decimal are interpreted as control codes, so you have to add 64 to any graphics data byte less than 32 decimal.

You would expect to be able to simply add the value 64 decimal to every graphics data byte; in other words, just set the seventh bit. This is risky because some variations within the 3000 product family interpret decimal 127, the Delete character, within a graphics sequence. The effect is to delete everything following the last line terminator. The safest course is:

byte_val < 32 then byte_val = byte_val + 64

WEIGHT	WIRE
1	1	!										!
2	2		!								!
4	3			!						!
8	4				!	!	!	!	!
16	5					!		!
32	6						!
		65	66	68	72	88	40	88	72	68	66	65

Figure 2-5Dot Column Coding

7265 Programmer’s Manual	29
Copyright © 2004 TallyGenicom	Chapter 2 ANSI