Epson 1000 Reference Manual page 43

Emulation Switch (ES)
This feature lets you use printer commands to switch directly
between the PostScript and LaserJet emulations.
To switch from LaserJet to PS emulation, send the following:
<ESC><DEL>
To switch from PS to LaserJet emulation, use your software to
send the following:
executive<CR>[<LF>]
serverdict<SP>begin<SP>0<SP>exitserver<CR>[<LF>]
executive<CR>[<LF>]
statusdict<SP>begin<CR>[<LF>]
5<SP>setsoftwareiomode<CR>[<LF>]
^D
Code in brackets [ ] are not absolutely necessary. <SP>
represents a space.
Epson Job Language command summary
The EJL mode enables your printer to switch to any emulation
available. To operate in EJL mode, follow the steps below:
1. Exit the current (or default) printer emulation and enter EJL
mode with the universal exit command.
2. If you wish, send other EJL commands, such as the comment
command, to the printer.
3. Send an EJL command to enter a new printer emulation
from the EJL mode.
Controlling Your Printer 1-27