Operator Control Panel Leds; Ocp Leds - DEC 4000 AXP Service Manual

2.1.2 Operator Control Panel LEDs

The OCP LEDs (Figure 2–3) are used to indicate the progress and result of
self-tests for Futurebus+, memory, CPU, and I/O modules. These LEDs are
the primary diagnostic tool for troubleshooting problems getting to the console
program.
A failure in the CPU, memory module, or I/O module can cause both the
I/O and CPU LEDs or I/O and memory LEDs to indicate self-test failures
even if only one of the modules is failing. If two LEDs are lit, the I/O
module is the more likely source of the failure.
Figure 2–3 OCP LEDs
Reset
Note
6-1 3 2 1 0
Halt
MEM
Power-On Diagnostics and System LEDs 2–7
DC On/Off
Switch
DC Power
LED
Self-Test
Status LEDs
0 1
CPU I/O
LJ-02008-TI0