2

VMEchip2

This register controls the VMEbus interrupter.

IRQL

These bits define the level of the VMEbus interrupt

 

generated by the VMEchip2. A VMEbus interrupt is

 

generated by writing the desired level to these bits. These

 

bits always read 0 and writing 0 to these bits has no effect.

IRQS

This bit is the IRQ status bit. When this bit is high, the

 

VMEbus interrupt has not been acknowledged. When this

 

bit is low, the VMEbus interrupt has been acknowledged.

 

This is a read-only status bit.

IRQC

This bit is VMEbus interrupt clear bit. When this bit is set

 

high, the VMEbus interrupt is removed. This feature is

 

only used when the IRQ1 broadcast mode is used. Normal

 

VMEbus interrupts should never be cleared. This bit

 

always reads 0 and writing a 0 to this bit has no effect.

IRQ1S

These bits control the function of the IRQ1 signal line on

 

the VMEbus:

 

0

The IRQ1 signal from the interrupter is

 

 

connected to the IRQ1 signal line on the

 

 

VMEbus.

 

1

The output from tick timer 1 is connected to

 

 

the IRQ1 signal line on the VMEbus.

 

2

The IRQ1 signal from the interrupter is

 

 

connected to the IRQ1 signal line on the

 

 

VMEbus.

 

3

The output from tick timer 2 is connected to

 

 

the IRQ1 signal line on the VMEbus.

2-62

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Motorola MVME172 manual Irql, Irqs, Irqc, IRQ1S