Epson 1500 - Manual (Page 246)

The following commands are available in FX emulation but not
in LQ emulation:
ESC1 7/72-inch line feed
ESC^ Select 9-pin graphics mode
ESCI Select character code table
The following commands are available in LQ emulation but not
in FX emulation:
ESC+ Select n/360-inch line spacing
The printer commands listed below function in a slightly
different way when used in the LQ or FX emulations. Also,
many of the commands that control the print position use
approximations because of the difference in print density
between the LQ and FX printers.
ESCG/ESCE
These commands produce identical bolding effects on your
printer. On an actual LQ series printer, these two commands
create slightly different effects and can be combined to produce
darker characters.
SI/ESC SI
These commands print 10 cpi characters in a 16.66 cpi font, and
12 cpi characters in a 20 cpi font. On an actual LQ/FX series
printer, these commands condense the font.
ESC x
This command is normally used to select between draft and LQ
quality with an LQ or FX printer. However, this command has
no effect on your printer’s print quality since all characters are
printed at 300 dpi (dots per inch).
LQ and FX Emulation Modes C-15