n Unidirectional printing

Unidirectional printing is a big word that means printing in one direction only. SR-lo/15 normally prints when the printhead is moving in both directions. But once in a while you may have an application where you are more concerned about how the vertical lines align than with how fast it prints. SR-lo/15 lets you make this choice. The table below shows the commands for controlling how SR-lo/15 prints.

 

Table 8-3

 

Printing

direction

commands

 

Function

Mode

Control code

Printinonedirection

STAR

<ESC>

“U” 1

 

IBM

< ESC >

“U” 1

Printinbothdirections

STAR

<ESC >

“U” 0

 

IBM

< ESC >

“U” 0

One-timeprintinone

STAR

<ESC>

“<”

direction

IBM

<ESC>

“<”

Try this program to see the difference that printing in one direction makes.

10 'Demo unidirectional printing.

20 LPRINT CHR$(27) "A" CHR$(7) ; 'Line spacing = 7/72".

30FOR I = 1 TO 18

44)LPRINT "I"

54) NEXT I

60LPRINT : LPRINT

70LPRINT CHR$(27) "U" CHR$( 1) ; 'Turn on unidirectional printing.

80FOR I = 1 TO 10

90LPRINT "I"

100NEXT I

110LPRINT CHR$(12) CHR$(27) 1’ @ II ,; 'Form feed, master reset.

Here is what you will get. The top line is printed bidirectionally,

and the bottom is printed undirectionally. You will have to look hard because there isn’t much difference.

Let’s analyze the program. Line 20 sets the line spacing to 7/72 of an inch so that the characters that we print will touch top to bottom. Lines 30-50 print 10 vertical line characters. Then line 70 sets one-direction printing and the vertical lines are printed

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