Quatech SSCLP-300 - Manual (Page 14)

The factory default is none of these jumpers applied, which allows for
software control of the clock multiplier via the Options Register. The Options
Register powerup default is for a standard times-1 clock of 1.8432 MHz for
compatibility with standard serial ports.
Figure 5 --- Clock multiplier jumper options
X8
X4
X2
J3
J4
J5
J2 SPAD
factory default
X8
X4
X2
J3
J4
J5
J2 SPAD
X8 mode
X8
X4
X2
J3
J4
J5
J2 SPAD
X4 mode
X8
X4
X2
J3
J4
J5
J2 SPAD
X2 mode
DSCLP/SSCLP-200/300 User's Manual 14