Answer:
From back in the days when a 64K computer would fill a room, punch cards were the standard input form, and it was called "Data Processing", managers of this business function had to hone their entrepreneurial and management skills. Opportunities for new applications to automate business units were, and still are everywhere. Even more so now, the breadth of responsibilities has grown to "anything plugged into the wall or floating in the air". Back in the data processing days, responsibilities were more automation/information based. But as communication was woven into the applications, infrastructure became an important part of the managerial responsibilities. Additionally, the convergence of telephony and video into this infrastructure further expanded the "stuff" to manage. And now weave in demands of employees wishing to utilize smart phones and be sure all employees have secure and unauthorized access for the right stuff at the right time free of the cyber-junk of the Internet.
Talking the language of the targeted business unit is essential. "Geek speak" will turn off non-IT managers from the necessary acceptance of proposed applications. The IT manager needs to understand the workings of the targeted business unit, translate it into specifications for the IT staff, make sure it will be integrated properly into other business units, and show essential ROI (return on Investment) for the company as a whole. Implemented applications need to undergo quality control and proper maintenance for reliability.