the DCU have surrounding barriers and interlocks to
prevent accidental key action. The DCU display
visually helps you to make the correct entries. The dot
matrix display has six 44-character lines of status and
maintenance data. You can monitor operations using
the ac plasma display and the indicators. Interfacing
(inspect and change and manual operations) with the
CPU/IOC and memory is accomplished using the key
switches. Monitoring capabilities include switch
settings, hardware availability, halts, jump stops,
breakpoints, and operator input. Remember that key
settings can interact with computer software.
This DCU is located in the front of the frame/
cabinet. The DCU has a built-in microprocessor with
five levels of controls and indications. They are as
follows:
l Loading and initiating operations
. Monitoring operations
l Status indications
l Operator interfacing
. Testing (self)
COMPUTER CONTROL PANELS
Computer control panels are used to power up the
CPU and for manual START, HALT, CLEAR, register
display, and bootstrapping. The controls can initiate and
monitor computer operations and load diagnostics
contained on magnetic tape from an external peripheral
unit. Then, from a data terminal, you can perform
diagnostics on the computer. Monitoring capabilities
include switch settings and display registers.
Remember that key settings can interact with computer
software. Some computer control panels limit their
access to authorized personnel only. A locked security
cover must be removed to gain access to the panel’s
switches. Figure 3-7 is an illustration of a computer
control panel. This computer control panel has three
levels of controls and indications. They areas follows:
l CPU power
l Initiate computer operations (includes
maintenance)
l Monitor computer operations
MAINTENANCE CONSOLES
Computer logic test sets (maintenance consoles)
allow you to operate the computer set under expanded,
and varied conditions, and at various speeds and various
operating modes. The maintenance console’s primary
purpose is to enable you to monitor instruction words
and input/output commands and their execution, and to
view the contents of various arithmetic and control
registers.
Monitoring capabilities include switch
settings, hardware availability, halts, jump stops,
breakpoints, and operator input. Remember that switch
settings can interact with computer software. The
maintenance console can be divided into three physical
areas. They are as follows:
Maintenance console control and indicator status
CPU portion
IOC portion
Refer to figure 3-8 for an illustration. This
maintenance console may be located up to 15 feet from
the computer set; but it is not designed to be mounted
permanently atop the computer’s cabinet. The
maintenance console receives its power from the
operator panel when online. When the maintenance
Figure 3-7.—Example of a computer control panel.
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