The development of Tera's MTA system was unusual. It respected the need for fast hardware and large shared memory, facilitating execution of the most demanding parallel application programs. But at the same time, it met the need for a clean machine model enabling calculated compiler optimizations and easy programming; and the need for novel architectural features necessary to support fast parallel system software. From its inception, system and application needs have molded the MTA architecture. The result is a system that offers high performance and ease of programming by virtue not only of fast physical hardware and flat shared memory, but also of the streamlined software systems that well utilize the features of the architecture intended to support them.