Epson Equity 286 PLUS - Manual (Page 76)

If you frequently use programs that require the processor to
operate at low speed or require the automatic speed change
when your computer is accessing a diskette, use SETUP to
change the processor speed. See Chapter 2 for instructions.
If you use these programs only occasionally, you should use the
keyboard commands or the ESPEED program (described below)
to change the processor speed.
Entering Keyboard Commands
You can change the processor speed by entering one of the
following commands at the MS-DOS prompt:
Ctrl Alt + Changes the processor speed to high
(12 MHz).
Ctrl Alt - Changes the processor speed to low
(6 MHz).
For the + and - characters, press the keys on the numeric
keypad. The commands do not work if you use the keys on the
main keyboard.
Note
You can use the commands listed above while you are
running a program. However, if you are running a program
that uses one of the same commands for another function,
you cannot use that command to change the processor speed.
For example, if you are running a program that uses the
Ctrl Alt - command to move the cursor, you cannot enter
Ctrl Alt - to change the processor speed to low. When you
exit the program, you can enter these commands at the
MS-DOS prompt to change the processor speed. Another
alternative is to use the ESPEED program, described below.
4-4 Enhancing System Operations