Applying Power
http://www.motorola.com/computer/literature 2-3
2
Switches
There are two switches (ABT and RST) located on the MVME240x front
panel.
ABT (S1)
When activated by software, the Abort switch,
ABT, can generate an
interrupt signal from the base board to the processor at a user-
programmable level. The interrupt is normally used to abort program
execution and return control to the debugger firmware located in the
MVME240x Flash memory. The interrupt signal reaches the processor
module via ISA bus interrupt line IRQ8
∗. The signal is also available from
the general purpose I/O port, which allows software to poll the Abort switch after
an IRQ8* interrupt and verify that it has been pressed.
The interrupter connected to the
ABT switch is an edge-sensitive circuit,
filtered to remove switch bounce.
RST (S2)
The Reset switch,
RST, resets all onboard devices and causes HRESET* to
be asserted in the MPC603 or MPC604. It also drives a
SYSRESET*
signal if the MVME240x VME processor module is the system controller.
The Universe ASIC includes both a global and a local reset driver. When
the Universe operates as the VMEbus system controller, the reset driver
provides a global system reset by asserting the VMEbus signal
SYSRESET*. A SYSRESET* signal may be generated by the RESET
switch, a power-up reset, a watchdog timeout, or by a control bit in the
Miscellaneous Control Register (MISC_CTL) in the Universe ASIC.
SYSRESET* remains asserted for at least 200 ms, as required by the
VMEbus specification.
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