3-27 Hardware Installation
External Memory Character Test
Note: This section is not applicable to NCR 5977 Graphical displays.
A separate checksum test is performed on the external Flash. A Character Set has its
own checksum byte stored in a specific block of a SPI flash sector.
If an error is discovered, testingstops and the Flash status is noted and saved for host
retrieval later using the Reset command. Any character set stored in the Flash is
considered invalid and any command received attempting to switch to one of these
character sets is treated as an invalid command and ignored.
Display Test
Note: This section is not applicable to NCR 5977 Graphical displays.
If the display is not connected to a host through a serial lines or USB, it runs an extra
test that turns on all pixels on the display (character cells) for about four seconds. This
permits a user to examine the display for any pixel failure, but doesn’t require him to
execute this test on every power up. The unit does not have the capability to determine
if the Display Test passed. Once diagnostic testing is completed, line states are returned
to normal and the firmware branches to its idle routine.
The host is able to detect a Retail Display failure by detecting exception conditions on
the RTS or Busy lines for at least three seconds.
Note: When the I/F receives a Reset command, only the Microcontroller Test and
External Memory Test Character are executed. The Display Test is not executed.
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