I-o-display-systems Basic I/O Product Manual de usuario descargar pdf (Pagina 20)

Setup & Installation 2

2-3(Vol.1)

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-duplex in 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.

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I-o-display-systems Basic I/O Product Manual de usuario Pagina 20