IBM was saved this quarter by one of its oldest product lines: the mainframe (IBM)

Killer sales of IBM's brand new System Z mainframe seriously buoyed up the company this quarter. IBM announced the new mainframe in January, but it didn't actually start shipping them until early March. Thanks to sales of these machines, its hardware business reported 30% year-over-year growth. That is on an constant currency basis (excluding the headwinds from a foreign exchange rate). It also excludes the revenue from the server business IBM sold to Lenovo. That business unit is now off the bo...