Epson Equity 4 User Manual page 50

Note
If the microprocessor in your system is a FQFP type, it is
surface-mounted on the main system board. This means that
if you install an OverDrive processor, you can install it in the
empty OverDrive socket. In this case, you need to disable the
original microprocessor by moving jumper J23 to position
You also need to make sure the jumper settings for J10,
2-3.
J11, and J12 are set correctly.
Processor speed jumper settings
Processor type
SX/25, DX2/50
(25 MHz)
DX/33, DX2/66
(33 MHz)
You need to change the processor speed jumper settings only if
you replace a 25 MHz processor with a 33 MHz processor.
2-8 Installing and Removing Options
J19
J20
Off
Off
Off
O n
J22
J21
On Off
Off
Off