Theory Of Operation; General - Control Data Corporation CDC CC63X Hardware Maintenance Manual

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THEORY OF OPERATION
GENERAL
The operational mode of the display terminal is determined by
parameters set in from the keyboard. Parameters may be selected
to initiate the resident CYBER mode, or to load and initiate host
programs. The terminal contains firmware for the- resident CYBER
mode; any other program must be downline-loaded from the host.
The terminal also contains firmware for self tests and for
loading host controlware.
Operations within the terminal are controlled by a micropro-
cessor. It can interface asynchronously with a higher-level
processor either directly or through a modern. The terminal is
multifunctional with the base unit being an alphanumeric
display. It contains interfaces for three small option boards
and two large option boards. These boards provide interfaces to
host computers, moderns, and peripheral equipment. Refer to
figure 4-1 for a block diagram of the display terminal.
The operator uses the keyboard to enter, change, or delete
information and to select initial operating parameters. The
terminal is multifunctional, having the capability for one
standard and six foreign languages and a variety of graphics
symbols. Terminal-operating parameters are entered from the
keyboard into a nonvolatile RAM, and read by the microprocessor.
There are three groups of operating parameters:
• Terminal installation parameters (select terminal-related
conditions, such as interfaces, memory option, or type of
peripheral to be used).
• Mode installation parameters (selects port rates and data
rates of each operating mode, such as CYBER).
• Mode operator parameters (determines conditions within
which selected mode will operate, i.e., on line, off
line, 80/132, cursor type, alert, etc.).
The terminal uses a Z80B microprocessor which controls all
operations inside the terminal. It directs the operations of
associated peripherals such as printers and modems. The micro-
processor uses 64K of dynamic RAM for instruction processing.
This RAM is dedicated for program operations and CRT refresh.
62940034 B
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