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The bank of four LEDs on the bottom of the CPU card displays a code that indicates which field
replaceable unit failed. When Test 1 is finished, all four LEDs are extinguished. The bank of
eight LEDs on the top of the CPU card is not used by Test 1 to indicate defective field
replaceable units. Any pattern that is displayed on the bank of eight LEDs during Test 1 should
be ignored. Table 3-2 lists the LED indications for Test 1 and their associated error codes.
Test 2
Test 2 is part of the VCP program also stored in the firmware EPROM on the A990 CPU card.
It begins execution upon successful completion of Test 1. Test 2 can also be initiated by an
operator command (%T) from VCP. Test 2 executes in two phases, and may take as long as 20
seconds to run, depending on the amount of memory installed.
The first phase of Test 2 checks the computer's basic instruction set, several internal flags, and the
Boot RAM. When the entire Boot RAM has been successfully tested, each location of Boot RAM
contains zeros.
The second phase of Test 2 tests main memory, the 110 Master of each interface card, and the
computer configuration. The 110 Master of each interface card is checked to ensure that data
transfer, flag, interrupt, and Direct Memory Access (DMA) functions are correctly processed.
If battery backup sustained main memory, phase two of Test 2 tests main memory in a non-
destructive manner. If main memory is not sustained by battery backup, a destructive memory
test is performed and main memory is effectively cleared (memory contains all zeros). On
successful completion of Test 2, the LEDs will be lit with a specific pattern. This pattern depends
on the startup configuration as selected by the BOOT SELECT switches (SW2). Refer to
Table 3-3 for the LED displays that indicate self-test passed.
If Test 2 detects a failure, the error code is displayed on the upper 8 LEDs (the lower 4 LEDs are
all oft). If a failure is detected during phase one of Test 2, test execution stops and the LEDs
indicate the type of failure by displaying a I-byte static error code (see Table 3-2). If a failure is
detected during phase two of Test 2, the VCP can still run if the VCP interface is functioning
properly and a VCP console is installed. The failure causes the LEDs to flash the error code (in
binary format) as well as display the error code in octal format in the message "Pretest Error
xxx.xxx.xxx.xxx" on the VCP console.
Each error message for phase two of Test 2 consists of four bytes of information. The information
is displayed on the LEDs using the scheme described in Figure 3-1. The first byte of the error
code is the main error code (memory error, 110 interface error, or interrupt error) and the second
byte is the subcode. Some of the error codes give additional information in bytes 3 and 4. For
example, error code 300 203 000 022 indicates that an 110 error (300) has occurred and that the
error was caused by duplicate select codes (203) and the duplicate select code was 22 (000 022).
An error code of 340201 000 000 indicates a memory error (340 201) in the first 32k block of
memory (000 000). Table 3-4 shows the LED failure indications for Test 2.
Service
3-5
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