Kurzweil PC88 - Page 27

Chapter 2 Diagnostics
Scanner Test
This test confirms scanner communications by sending
data to the scanner. After processing the data, the scanner
sends a result back to the main processor. If the returned
value is not as expected or the scanner does not reply as
expected, the test fails.
Failure of this test indicates a failure of the main
processor (68301, U21), the scanner (37451, U17) or traces
linking the two serial ports of these devices. There are no
other components involved in the test. Note that failed
scanner communications will likely disable operating the
diagnostics from the control panel, since control panel
signals must be read and written through the scanner.
Parallel I/O (PI/O) Test
The Parallel I/O Test writes each of two
complementary bit patterns to bits 0-7 of the 68301's
parallel port, verifying that the pins were able to change to
the desired state.
Failure of this test could be caused by the main
processor or the circuitry connected to the parallel port.
Timer Test
The Timer Test confirms the operation of the 68301's
internal timers.
Failure of this test is caused by a damaged 68301.
PC88 Service Manual
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