Printer; Keyboard; Display Interface Module (Dim); 98760A Display Alpha And Graphics - HP 9020 Service Manual

3-10
Testing and Troubleshooting
During system initialization all mapped-out blocks of RAM on each memory controller are checked.
If a mapped-out block is non-functional, the message
Heal e rOve rf I ow on
Me
#N
is displayed.
After system initialization is complete and the computer is in use, additional memory error manage-
ment is performed. The operating system reports the memory controller number and the RAM
location
~hen
a double-bit memory error occurs.
Printer
The self-test supervisory code verifies the printer's connection to the 110 bus at powerup. It then
reads the self-test status register. The code issues a message to the user if a failure is detected.
Keyboard
The self-test supervisory code tests registers on the keyboard. 110 bus interconnect is tested via a
special register on the keyboard. Data is written to and read from this register (loopback). Interface
control lines are tested and keyboard self-test results are obtained by writing a command to the
keyboard which causes it to report self-test results.
The code issues a message to the user if a failure is detected. System diagnostics perform further
tests of the keyboard electronics.
Display Interface Module (DIM)
The STSC tests the DIM interface to the 110 bus and initiates the self-test of the line buffer chip. The
code also tests the display buffer memory. The code issues a message to the user if a failure is
detected.
98760A Display Alpha and Graphics
The STSC tests the alpha/interface board and the graphics/digital video board. The test initializes
the alpha controller and checks status. It performs alpha memory tests with four patterns: all 0' s, all
l' s, alternating l' sand 0' s, and alternating 0' sand l' s.
The test checks graphics status and initializes the monitor. It checks the three memory functions: set,
clear, and complement. It tests the vector generator in the graphics controller and then writes eight
small vectors into each memory plane in each of the three memory functions. The test reads the
words and checks them.
The STSC continually checks for timeout errors in both DMA and direct 110 modes. The code
issues a message to the user if a failure occurs.
9130K Flexible Disc Drive/Controller Card
The STSC tests the 110 bus and the 9130K controller card interface to the lOP. After verifying bus
integrity, the code reads self-test status from the controller card's self-test register. The code issues a
message to the user in case of a failure.
Winchester Fixed Disc Drive/Controller Assembly
The STSC tests the 110 bus and the controller assembly interface to the lOP. After verifying bus
integrity, the code reads self-test status from the controller assembly's self-test register. The code
issues a message to the user in case of a failure.