problem with the porting of rtems

[Francesco Poletti]

Hi,
I can't understund why in the function void _CPU_ISR_install_vector
(which is in the /cpukit/score/cpu/arm/cpu.c file) there's this
instructions:
-long *VectorTable= (long*) (MAX_EXCEPTIONS * 4);

and VectorTable is the address base from which is place the
exceptiontable,but the arm have this excetiontable starting at hte
address 0.Why is like this? 

Another question Why at the Irq is associated the
_Exception_Handler_Abort, I don't understand very well by wich mechanism
is called the real irq_handler, if there's one.

Thank to all for the answer...
Francesco Poletti