Chapter 2
SYSTEM CONFIGURATIONS
This chapter contains general rules governing the attachment and powering of various configurations. The reasons for the procedures should be apparent from the explanations given in this Chapter, but if the reasons are not apparent a more complete explanation of the principles of operation may be consulted in APPENDIX 11.
Communication between a peripheral and the computer must conform to the limitations imposed by the hardware. For example, the speed of communication is always limited. The limitations are different for different peripherals. The computer must "know" what peripheral it is communicating with and how to compose and interpret messages to and from that peripheral. Some of the information about the peripheral that permits the computer to handle it is in computer memory, but initially comes from different sources. For example, the diskette and the disk drive are the source of information for handling communications with the disk drive. This information is passed to computer memory when the computer console is powered on provided the disk drive is already powered on and contains an appropriate diskette.
Information about the serial ports of the ATARI 850 Interface Module is contained in the interface Module itself and is transferred to computer memory when the computer console is powered on. Therefore~ you must power on the interface Module before you power on the console, if you intend to use a serial port. You may unnecessarily boot the Interface Module. That is you may turn on the Interface Module then the computer console, but not use a serial port. This does no harm, but it "wastes" RAM (1762 bytes) by loading the unused RS-232-C handler.
You may wish to use the Interface Module to interface to a non-ATARI device. In that case, you must make sure that the device is compatible with the Interface Module. You must examine the specifications of your device. You may also have to make or specify a cable to connect the Interface Module with your device, and APPENDIX 11 contains guidelines and connector information on this subject.