Flash storage is integrated for the first time on System z® as a card in the EC12 I/O drawer. This provides a number of functions and benefits in the immediate product, in addition to laying a foundation for further system benefits in future generations of System z systems. Enabling flash MLC (multilevel cell) technology as SCM (storage class memory) in an enterprise-class product required myriad diverse individual technological advances, together with a series of system design features. Extreme care and attention were paid to ensure that the required level of System z reliability was maintained. As with legacy I/O, the programming interface is subchannel-based. The subchannel programming interface is expanded with new architecture via the extended asynchronous-data-move facility. Operating system changes were required to enable exploitation of the features that this new system technology offers. These individual hardware, firmware, and software design aspects are described in this paper, along with the overall functionality and system-level value of this new technology.