Kurzweil K2000 Service Manual page 61

SECTION 4
DIAGSO_4.DOC 12/22/92
will be interrupted and hold temporarily and will resume when any front panel
button is pressed.
As the continuous tests are running, the bottom line of the display will
indicate the number of tests that have been completed, and the number of
failures that have occurred.
4.13 TEST TYPES
The tests described in this section are of three types, referred to as RAM
tests, ROM tests, and 1/0 tests. Memory tests check the physical memory
addresses of the data corresponding to various components. This is done by
writing an arbitrary test data pattern to memory and reading it back,
comparing the written data to the read data. ROM tests involve comparing the
data stored in the ROM components to a checksum. 1/0 tests also send a test
data pattern from the central processor to the component(s) being tested, and
check whether the data are being exchanged properly between the central
processor and the tested component(s).
4.13.1 Memory tests
There are two stages to a memory test: the data test, and the address t~st.
In the data test, a test data pattern is written from the processor to the
memory component being tested. The diagnostic software expects the data
pattern that's written to memory to be read back exactly as it was written.
If this is the case, the test passes. If the observed data (the data read
from memory) differ from the expected data (the data written to memory), the
test fails.
When a data failure occurs, it is displayed in the following format: the
memory address where the failure occurred; the expected hex value at that
address; the actual observed value at that address. See Figure 4.5 for an
example.
Figure 4.5. Data Fai~ure
In the address test, the central processor (CPU-a Motorola 68301) checks every
memory address related to the component being tested. A test data pattern is
written to each address, and then read back. The diagnostic software expects
the data pattern to be read back from the same address to which it was sent.
If the observed address (the address read from) matches the expected address
(the address written to), the test passes. If the observed address does not
match the expected address, the test fails. Address failures are displayed
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