Epson Equity II - Manual (Page 59)

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Math coprocessor clock speed. If you or your dealer installs an 80287
math coprocessor, you may need to set the jumpers for a different clock
speed. The jumpers determine the speed of the coprocessor.
As it is easy to damage a math coprocessor, you should have your dealer
install it for you. In addition to checking the jumper settings, you or the
dealer should also use the diagnostics’ Setup program to change the
settings in the CMOS RAM, and use the System Diagnostics program
to test the coprocessor.
Table A-2 shows the functions for the jumpers on the main circuit
board.
Table A-2. Main circuit board jumper settings
Jumper number Function
1 2 3 4 5
A 1 wait state for EPROM
access
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2 wait states for EPROM access
A A 1 wait
state for 16-bit option card *
B A 2 wait states for 16-bit option card
A B 3 wait states for 16-bit option card
B B 4 wait states for 16-bit option card
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A A Set coprocessor clock at 8 MHz *
B B Set coprocessor at 1/3 of CPU speed
* Default setting
To access the main circuit board jumpers, you must remove the memory
card from the computer, as described above. Do not try to access the jumpers
while this card is still in the computer.
Figure A-5 shows the locations of jumpers J1-J5 on the main circuit
board. Refer to Table A-2 above to set them as needed.
When you finish changing the jumpers, carefully replace the memory
card in its slot and secure it with the retaining screw.
User’s Guide A-5