The computer control system consists of one or more personal computers. Each computer runs a copy of the Linux operating system. Linux is a UNIX style operating system that runs on x86 class machines.

If there is more than one computer in the system, they are interconnected by a network. One computer contains the control system software and user files. The rest of the computers access that computer through the network by using NFS. Throughout the rest of the manual, the computer containing the control system software and the user files will be refered to as the file server.

The network may also have terminal servers connected to it. Terminal servers are boxes that have a number of serial ports and a network connection. They allow incoming and outgoing connections to be made between the devices attached to serial ports and the network.

Starting the control system requires that the file server be started first, followed by the rest of the computers and the terminal servers. After all of the computers and terminal servers are up and operating, the accelerator control system may be started.

The accelerator control system is composed of a database manager program and groups of programs that communicate between the database manager and the hardware.

Linux, as well as most other large powerful operating systems, requires an organized startup and shutdown.

When the system is started, various housekeeping programs are loaded and executed. The file system is checked to insure it wasn't damaged when the system was previously turned off. These and other functions are performed in the startup process.

Shutdown is the opposite of startup. Disk buffers that are currently in memory are written back to the disk drive. Housekeeping programs are terminated and the information that has been collected is properly stored. These and other functions are done by the shutdown process.