User models can kick fast-adc IOP models that use too many IPC parts.
From Lee McCuller running on CyMAC at MIT:
IOP fails when user model starts with ADC channel hopping
The IOP only fails if there are some calculations made in the IOP and 24 IPC SHMEM senders (are these IPCx?)
If the calculations are left the same and the IPCx SHMEMs are reduced to 9, the user model does not cause the IOP to fail.