What type of device used to interface a parallel data format with an external equipments serial format?
There are several meanings of parallel device. It can mean having two or more computers working on the same problem at the same time. This is called parallel computing. Or it can mean any device hooked up to the parallel port on a computer. Parallel ports are fairly obsolete, so you are less likely to see this version of parallel device in the future.
Distinguish between a microcomputer interface and the channel-control unit architecture used on mainframes?
An external data storage device is one that is not located inside the computer, but is connected outside of the case via a port or cable. There are many such devices, including USB Flash drives, hard drives, floppy drives, and tape drives. They can be connected through a variety of ports, including USB, FireWire, eSATA, or the parallel port.
An example of a device driver would be the interface between the Windows Operating System and the computers Network Interface Card. Device drivers are used to eliminate the need for the Operating System to know how to "talk" with a given device. The Operating System makes standard calls (called API calls) which are intercepted by the device driver, translated into something the device can understand and passed to the device.
A "Natural User Interface" is a hypothetical user interface model that would allow a human operator of a device or control system to interact with that device in the same way in which one would interact with one's immediate environment. In theory, a natural user interface would not require any education or training to be used.