N Processors are sharing a bus. We can model a system with or without
request resubmissions. Without resubmissions we can use the Null Binomial
Model which is identical with the first iteration of the model with
resubmissions. Therefore the first click on 'Iterate' will deliver the
Null Binomial solution and every consecutive click improves the solution
towards the model with resubmission.
Rho, the bus occupancy of a single processor is calculated automatically
after the first two values (BTT, PT) are entered. After entering N, BTT
and PT, iterate to get the final solution.