|The THREE_C package was developed for use on the 104-cm telescope of the Stephen F. Austin State University Observatory. It is intended to provide complete and integrated control of the telescope and its primary function of photoelectric photometry through a menu driven operating system. The software was developed in C with an assembly language interface to control the interrupt driven functions and the pulse counting. The telescope control assumes the existence of the Superior Electric Control system, and communicates with it over a 1200 baud RS232 line. The complete list of slot cards and their function follows. The order is left to right as viewed from the front of the computer.
EIDE Slot 1
The leads coming from it are labeled RA/DEC, PC0, PC1, and PC2. All telescope motions except slew are controlled using the Pulse at External Rate feature of the Superior Indexer Card. When a frequency is provided to the appropriate pin of the indexer card (either Right Ascension [RA]* or Declination [DEC]), the motor will turn at half this frequency. The leads labeled RA and DEC, then, provide frequency outputs to the indexer cards. The leads labeled PC0 (left), PC1 (center), and PC2 (right) are the input from each of the amplifier/discriminator circuit on the three channel photometer. The CTM5 card has been programmed to act as the pulse counter.
EIDE Slot 2
This card provides twelve eight-bit parallel ports. The cables provided have very different function. The cable labeled FW (9-pin DIN) contains output lines used to drive the stepper motors on the photometer filter wheels as well as the focus motor on the secondary mirror. The cable labeled HP (9-pin DIN) contains input lines from the Hand Paddle. A third cable labeled XY (9-pin DIN) drives the offset stages of the three channel photometer. The final cable (round connector) controls the dome power circuit and the dome sense circuit used for automated dome rotation.
EIDE Slot 3
This card can be programmed to serve as a RAM Drive for data storage. It is not currently used. The serial port on the card is used as COM3: to read the Heath Most Accurate Clock.
PCI Slot 1
This is necessary to support the CCD camera used for pattern recognition that is attached to the eight-inch finder.
PCI Slot 2
This card reads the EDC-1000 camera from Electrim.