Diagnostics
Asynchronous Communications Port Test
Baud rate clock
Internal transmit/receive
Modem control fines
External loopback (requires loopback connector)
Additional Diagnostics
The diagnostic program hard disk tests are all nondestructive except on the diagnostic
cylinder. The tests perform seek tests, head tests, and controller tests, but do not perform
read/write tests on the entire media. Additional tests for the hard disk are contained in the
hard disk format system, which is described later in this appendix.
Diagnostic Error Codes
When an error is detected by the diagnostics system, a twobyte hexadecimal code is
displayed. The first byte is the class of the error and the second byte is the sub-class. The
error code class generally corresponds to a specific hardware system or group of hardware
systems. For example, class one (01) is used for the system planar board. The last byte of
the code (sub-class) describes the actual test that failed on the specified peripheral. For
example, error 0108 indicates that the 8253 counter test failed during the system planar
board test.
D-6 Diagnostics