6100 BSC Programming Manual

6100 BSC Concepts and Context
Message Formats
The most common reason for a point-to-point link is to let the
two stations exchange application data. For example, a mainframe
sends text to a terminal for presentation on its screen, and
receives from the terminal the data it needs to accomplish a
transaction. Alternatively, one station might act as a message
switch, accepting data and routing it to one or more other
stations. The "text" of each message might then be transparent
to the station doing the switching; for instance, it might use a
character code foreign to that station. Figure 1-3 shows some
applications of point-to-point links.
A B
C
D E
A
A
D
E
S5066-002
• Computer exchanges application data with computer ,
terminal , and printer over point-to-point links.
• Computer is also a message switch, letting computer
exchange data with the other three stations.
Message to A from E
Message to E from A
Message
to C from E
Message
to B from C
Message to A from B
Message to B from A
Message
to A from D
Message
to D from A
B
C
Figure 1-3. Point-to-Point Links
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