HP E1313A Manual page 378

General Register
Any of the A16 registers can be read from while the module is in any state
(see the Control Processor State Diagram on page 381). You should avoid
Access
accessing the module's A24 areas other than the CVT while the module is
scanning. In order to avoid unpredictable results, the Scan Control, Card
Control, and Trigger Mode Registers should not be written to unless the
module is in the Waiting for Command State. To assure this, use the
following procedure to write to these registers.
Figure D-4. General Register Access
Appendix D Register-Based Programming 377
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