Optional Components; Communications Controllers - Digital Equipment MicroVAX 3600 Operation

1.3.2 Optional Components
System options can include multiples of components that are part of the base
system (for example, additional memory modules or disk drives) and the
following kinds of options:
•
Communications controllers
• Real-time controllers
• Printer interfaces
1.3.2.1 Communications Controllers
Besides the console serial line, most systems have additional communications
controllers for connecting additional terminals, and for communicating with
other systems over telephone or network lines. Communications controllers
provide standard interfaces between peripheral devices and the system. Many
communications controllers provide support for multiple data lines.
The following types of communications controllers are available:
•
Asynchronous serial controllers
•
Synchronous serial controllers
•
DECservers
• Network controllers
Serial controllers transmit data one character at a time. A device at the
transmitting end breaks bytes of data into bits. A device at the receiving end
assembles incoming bits into bytes of data.
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Asynchronous Serial Controllers
Asynchronous serial controllers provide low-speed connections between
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peripheral devices and the system. Asynchronous communication between
the system and the peripheral depends on recognition of a pattern of start
and stop bits, not on a time interval.
Asynchronous serial controllers may be divided into those without modem
support and those with modem support.
You use serial controllers without modem support to connect additional
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terminals and printers to your system. For example, the CXA 16 module
provides connections for up to 16 serial lines with no modem support.
NOTE: Printers equipped with a microprocessor (intelligent printers) may require
modem control signals to function correctly. Do not attach a printer requiring
1-26 MicroVAX 3600 VAXserver 3600/3602 Operation