I'm looking for an explanation of the different functionality in versions of a application called VMAC (Verix blah blah blah), also called "comm server", which is used on Verifone payment terminals. I've got terminals with versions 1.7 and 3.3 of VMAC, and I'm unaware of the differences.
If someone is a Verifone expert, it would be helpful to know how much of the communication with the processing host vs the merchant services provider's application.