NAME

arb.diag − Test the arbitration circuitry

DESCRIPTION

This test assures that bus arbitration works correctly by using two (or more) CPU boards to access an area of shared memory.  Only shared read-access to memory is tested.  This test also assures that the processor that requested a particular data word actually receives it. 

DETAILS

The test is conducted by having five individual memory spaces, called the A space, a Shared space, and three B spaces.  The main processor initializes the shared space such that each memory location contains a value that is equivalent to its offset from the beginning of that memory space.  Then it starts each slave processor to run.  Each slave processor reads the shared space, one memory location at a time, and writes into its own (B) space, a value that is the complement of the data read from the shared space. 

The boot processor does the same, writing a copy of the Shared space data into its (A) space.  Then each processor proceeds to check that the data in its own space matches a copy of, or the data in the shared space.  Finally, each processor checks the other processor’s memory space to make sure that each other processor has been successful.  In this manner, if one processor is not functioning correctly, another processor can report the failure. 

BOARDS THAT MUST BE INSTALLED

Requires 2 CPU boards and one memory board, and a known good I/O board for downloading the test. 

SPECIAL COMMAND LINE PARAMETERS

None

MENU ITEMS SPECIFIC TO THIS TEST

arb −Run the arbitration test. 

INTERPRETING THE ERROR CODES

The following errors may be generated by this test.  (The actual error wording may differ, however the type of error is as summarized here.) 

100Incorrect board ID sensed (Only the Boot CPU can run this test)

101Count of non-boot processors does not match the number of responses received (Two CPUs responding to the same ID?) 

102Incorrect value found in first address of the shared memory buffer (Memory addressing or arbiter problem)

104Slave processor timeout occured, no acknowledge signal received when master tried to start slave processor (Slave processor not responding)

105No response from any slave processor, so no test was run (This test needs more than one CPU)

106Boot CPU found a miscompare in another processor’s memory space (Maybe that slave CPU is not working)

108CPU other than the boot CPU did not begin its test run within a specific period (Maybe that slave CPU is not functioning)

110Slave processor found a miscompare in its own address space (Memory or arbiter error)

112Slave processor found a miscompare in boot processor’s memory space (Memory or arbiter error)

114Unknown error detected by one (identified) processor (This error should not occur.  It means an error was sensed but that the type of error was not identified.) 

116Data miscompare error (Can be generated by master or slave, should be followed by error 106, 110, or 112, if not followed by those errors, it is the boot processor that found the problem)

September 02, 1992