Jumper Configurations
Table A-1
Jumper Descriptions (continued).
JUMPER #
DESCRIPTION
W34
Install W34 to bring the 1.19318 MHz clock to
the timer 2 clock input and to J3 pin 8. Remove
W34 to disconnect this clock. This requires an
external source on J3 pin 8 to clock the timer and
is necessary to prevent an open circuit on the
clock input. Factory default installs this jumper.
W34
Function
IN †
Timer 2 clock input is 1.19318 MHz
OUT
Timer 2 clock input is from J3 pin 8
W35(A,B)
Select W35B to battery back the two RAM sock-
ets at locations 7D1 and 9D1 with the optional
battery installed (also install W12 if using the
battery).
Select W35A to back up only the
32 Kbyte static RAM at location 7D2 on the
ZT 8809A.
If no battery is installed, select
W35A, the factory default.
W35A
35B
Function
IN †
OUT
Battery back the 32 Kbyte RAM and
timekeeper only
OUT
IN
Battery back the above plus sockets
7D1 and 9D1
Note: If no battery is installed, select W35A.
A-25
