Table of Contents
Advertisement
HP 27130A
DIAGNOSTICS
The MUX
self -test
performs
diagnostic
tests
to
detect malfunctions. Self -test is executed
'offline'. That is, it does not run concurrent with the standard MUX firmware. It is executed on a
hardware reset of the card following a CHANNEL I/O "Addressed Device Clear" (DCL/DEN) or
"Reset" (RES) assertion.
It
exercises the major components and data paths on the card.
If
no
problems are found, the card is made functional and the standard MUX firmware is invoked. If a
hardware malfunction is detected, the card is left disabled, indicating that self -test failed.
The following tests are performed by self -test:
* ROM test: To insure that no bits have changed on the ROM (EPROM), a cyclic redundancy
check is done using the polynomial X**16+X**2+X+1. The test is performed in 4K seg-
ments to ensure accuracy of the CRC.
* RAM test: RAM is checked for both stuck-at-O and stuck-at-l conditions and address decoder
failures.
* ASYNC SIO Loopback test Verifies that the SIO can perform basic asynchronous transmit
and receive functions.
If
a loopback hood is sensed, loopback is performed using both the inter-
nal and external line drivers.
* CTC test: Detects stuck-at faults in the data lines, system control) interrupt control (except CTC
1 and 2, which have no interrupt capability), and the four channel signals, for each CTC.
* BIC test: Checks the Backplane Interface Circuit (BIC) for functional faults. Checks for some
stuck-at faults in internal BIC registers. The BIC circuitry is tested using the internalloopback
functionality built into it. Testing of I/O channel driver and receiver hardware external to the
BIC is not done by self -test. The combination of the host diagnostic and MUX loopback support
in the 'standard' MUX firmware will exercise the host/MUX interface.
* MIC test: Checks the Memory Interface Circuit (MIC) for functional faults. The registers in the
MIC which can be read and written to are checked for stuck-at-l and stuck-at-O faults, and
both read and write DMA on both DMA channels are tested using SIO channel O.
Some
MIC registers cannot be tested (they are write only») and the DMA test does not exercise all pos-
sible DMA configurations (time limitations).
Upon successful completion) self -test will set 'Passed Self -Test' status (PST), turn off the LED on
the card) and invoke the standard MUX firmware. The standard firmware will then wait for the
host to 'teach' it its Peripheral Address (P A).
If self -test fails, the LED is left on, the 'Passed Self -Test' status (PST) is not set, and the Z80 is
)Halted'.
4-20
Advertisement
Table of Contents
