Theory Of Operation; Controller; Controller Board - Control Data Corporation INFORMATION SYSTEMS TERMINAL II Hardware Maintenance Manual

THEORY OF OPERATION
The maintenance philosophy for the terminal calls for
troubleshooting and parts replacement down to the chip
level in some cases. A block diagram of the terminal is
presented in figure 4-1. This section describes the basic
functional modules and chips that are replaceable in the
terminal without a detailed analysis of their internal
operation. The information is presented in the following
order:
• Controller
• Communication Interface/Internal Modem
• Operators Panel
• Touchpanel
• Power Supply
• Video Monitor
• Keyboard
CONTROLLER
The controller portion of the terminal consists of two
printed-circuit logic boards (PCBs): the controller board
and the video board. The following paragraphs describe
some of their features and capabilities.
CONTROLLER BOARD
This board provides the control function and processing
capability required to support the input and output opera-
tions as well as to manage their interactions.
Examples of control functions are:
• Character generation
• Line generation
• Instruction decoding and execution
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4-1
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