drvAscii ipacAddCarrier routine

[John Faucett <faucett@lanl.gov>]

I'm using drvIpac 1.7 on an MV167 with EPICS 3.13.4.  Since I'm using 
the GreenSpring IP-Octal card, extra memory needs to be allocated. 
In the startup file, the command

ipacAddCarrier &vipc616,"0xC000,0xA00000,512"

is executed.  If there's nothing but the IP-Octal on the crate, then 
that works fine.  But once many other modules are added to the crate, 
then a memory access error stops the boot at this point.  The problem 
is that I don't know a rational method to choose the address 
parameters.  So far I've just used trial and error.  Does anyone have 
any guidance?