Timer Interrupt Test; Chip Tests - HP 3000 Series Installation And Service Manual

Ma intenance
5-6. ROM Test
The second portion of the self-test program tests a calculated
checksum. The ROM contains a "burned-in" constant that is used
in the calculation of the current ROM checksum. A net result of
ze ro should result when the old and new checksums are compared.
This is the only test conducted on the ROM. LED indicator 6 is
lighted at the start of this test. If the test is successful,
LED indicators 5 and 6 are lighted. If the test fails, indicator
6 stays lit.
5-7. Timer Interrupt Test
The third portion of the self-test program checks to determine
that a timer interrupt occurs. This test includes a timing
routine that executes in 12 milliseconds. During that interval,
a timer interrupt should have occurred. This test does not check
the accuracy of the timer, but rather it verifies that the in-
terrupt has actually occurred. At the start of the test, LEDs 5
and 6 are lighted. At the successful completion of the test, LED
3 is 1 igh ted and LEDs 5 and 6 are tur ned off. I f the test fa ils,
LEDs 5 and 6 are left on.
5-8. RAM Test
The fourth portion of the self-test program is the RAM Test,
which consists of two routines. In the fir$t routine, each
memory location has its address written into it and then read
from it, starting at location 0001 and progressing to 3FFF. The
second routine fills memory downward with the complement of the
address and reads it upward. LED indicator 3 is lighted at the
start of the test. If the test is successful, LED indicator 4 is
lighted and indicator 3 is turned off. If it fails, LED in-
dicator 3 stays lit.
A further test is performed on the memory refresh circuitry.
Every 2 milliseconds, all of memory must be read from and written
to by the hardware to prevent data loss. If the refresh
cir~
cuitry were to fail, it would show up as a failure in
~
read from
memory after this test wrote to memory.
5-9. Chip Tests
The fifth portion of the self-test program performs tests on the
remaining portions of the peA board, namely the communication
chips and the I/O controllers. LED indicator 4 is lighted at the
start of these tests. As each individual test in this group is
completed, the LEDs are incremented. If all of the tests are
successful, LEDs 0 and 7 are lighted. If anyone fails, the
tests are not halted, but the appropriate LEDs are lighted.
5-4