Setup & Installation 2
COMMUNICATING WITH THE BASIC I/O:
The BASIC I/O is designed to serve as an intelligent I/O front end for a Host computer (Typically a P.C.). The host and BASIC I/O communicate over a serial link. This interchange is half-duplexin nature; that is to say the host and BASIC I/O will never be transmitting at the exact same time. Further, the communications protocol is considered “speak-only-when- spoken-to”; the Host must poll the BASIC I/O whenever it needs fresh data. This polling is accomplished when the host sends an instruction to the BASIC I/O. The BASIC I/O will then generate a reply. Each valid instruction will illicit a corresponding response. The integrity of this communication is verified using message content checksums.
The serial communication is a form of ASCII printable characters and makes heavy use of the hexadecimal numbering system. The format of the ASCII characters used is: One start bit, eight data bits, one stop bit, and no parity.
