IBM Personal Computer AT Manual To Operations page 219

ESCn
ESC
0
The value of n must be between 1 and 127.
ESC N must be reset anytime the page
length is changed by ESC C (Set Page
Length in Lines) or by ESC CO (Set Page
Length in Inches).
LPRINT CHR$(27);CHR$(78);CHR$(n);
Set Aspect Ratio
Format: ESC n;x;
Sets the printer to a 5:6 or 1: 1 aspect ratio.
When x is 1, the aspect ratio is set to 1: 1 ;
when x is 0, the aspect ratio is set to 5:6.
With the 5:6 aspect ratio selected, graphics
are printed to match the shape that appears
on the display. The 1: 1 aspect ratio is
recommended for bit-image graphics to
improve quality and simplify bit-position
calculations. The power-on default is the
5:6 aspect ratio.
Note: The Color Printer operates only
on the least significant bit of n.
Therefore, any odd-numbered ASCII
decimal value gives the same result as
n= 1, and any even-numbered ASCII
decimal value gives the same result as
n=O.
LPRINT CHR$(27);CHR$(11 O);CHR$(x);
Cancel Automatic Perforation-Skip
Cancels the automatic perforation-skip
function.
LPRINT CHR$(27);CHR$(79);
Color Printer 1-109