How are the “Various High-Speed TTL I/O Ports for Precision Control” used?
These are ports that duplicate functions available to the user on the front panel. For the most part, these ports aren’t necessary for normal operation, but may come in handy for special applications. Nevertheless, two of the ports are commonly used and are very handy. The Epoch output port outputs a pulse whenever the PN sequence begins to repeat itself. This can be used to trigger an oscilloscope when observing the sequence on the scope. The other is the Run input port, which can be used to trigger a burst of chips when Burst Mode is selected. The remaining I/O control ports operate as follows: A rising-edge on the Preset input port will stop the shift register and load it with the Initial Fill (a.k.a. Preset Code), as set by the user. A rising edge on the Run input port will start the shift register, or stop it if it is already running. In direct sequence applications, the user may apply a data source to the Data input port, and this is modulo-2 added with the PN sequence to produce
