Service manual

UCW and Ultraview 1700 Monitors — Service Manual
3-10
Power Failure Operation
The power supply within the monitor chassis provides a digital PFAIL signal to the CPU PCBA to
indicate that a power failure condition is imminent. This signal is asserted by the power supply if its
AC input power fails for more than one cycle or if the monitor is switched OFF. This signal is
provided through a power supervisor IC to the MPC860 as an interrupt, causing the processor to
take immediate power failure action.
The power supply will continue to provide DC power to the CPU PCBA for a minimum of one
millisecond after the power failure condition is detected. The host processor must complete all
power failure actions during this time.
Hard Reset Configuration Word
At the rising edge of hard reset (HRESET), the 860 processor samples the rstconfg pin. The 860
processor has this pin tied low, which tells the 860 to read data bus bits 15-0 to determine its basic
post-reset configuration. Resistor pullups on the bus pull certain bits high; the others are pulled low
by weak internal pulldowns. The 860 is set to read the following:
Bits 15 – 0 = 0000 0110 1000 0010
If any of these bits are stuck in the wrong state at reset, the 860 will not properly boot. The detailed
meaning of each bit is explained in the MPC860 User’s Manual.
Interrupts
The MPC860 processor has two on-chip interrupt controllers, one in the System Interface Unit (SIU)
and a second controller within the Channel Processor Module (CPM). These handle interrupts on
specific input pins of the MPC860. Some interrupts are also routed through the interrupt controller in
the ISA bridge.
Figure 3-5: Interrupt connections
VGA
keyboard
audio
mouse
ISA
controller
supervisor IC
MPC
860
C15
C14
C9
C8
C5
C4
sdlc rts
video drq
uart cts
uart cd
irts cts
e-net
860/PCI
bridge
c11
c10
uart dsr