Quatech Asynchronous Communications Adapter DSC-200/300 - Manual (Page 11)

2.4 Clock Rate and Optional Registers
Figure 3 shows the jumper configuration as shipped from the factory, with two
spare jumpers applied in neutral positions. Remove one or both and apply as shown
in following subsections to set optional features.
SPAD
X2
X4
X8
J10
J11
J12
J13
Figure 3 --- Factory default clock rate and options settings
2.4.1 Enable Scratchpad Register (SPAD, J13)
In the default configuration, an Interrupt Status Register and an Options Register
(see page 10) replace the scratchpad (base address + 7) of each UART. If the SPAD
jumper is applied as in Figure 4, the UART scratchpad registers are enabled, and the
Interrupt Status Register and the Options Register are not available.
SPAD
X2
X4
X8
J10
J11
J12
J13
Figure 4 --- Enable scratchpad registers
Quatech DSC-200/300 User's Manual 11