z/Architecture refers to the foundation for every z/System processor and every operating system running on it. It is an extension to the system 360, 370, 390, and ESA 390 architecture. It was announced in late 2000 and as of the filming of this video, it is the latest and most current generation architecture. This architecture spells out how the hardware and operating systems interact with one another, which includes defining and using system resources, executing IO instructions, handling exception conditions, and supervising the scheduling and execution of multiple programs. In this series, we'll mainly be talking about the z/OS operating system. The z/Architecture demonstrates an evolutionary approach. Even though it grows in functionality, it still provides a high degree of compatibility with previous iterations, such as ESA 390, System 390, way back to System 360. While the platform is 64 bit, 31 bit and even 24-bit applications can run unmodified in certain cases on a number of z/Series processors. The z/Architecture represents the latest set of instructions, also known as the instruction set available for z/Machines, including the newest ones, which support 64-bit addressing. The architecture of a z/System is a physical implementation of that z/Architecture representing the latest and greatest in capability. z/OS, the operating system is built to use the architecture's instruction sets specifically. Wrapping this all back, the operating system uses the instruction set which is prescribed by the architecture. The physical implementation of the architecture is a z/System. This is truly a purpose-built environment where every aspect comes together to evolve the platform. We mentioned how the z/Architecture demonstrates an evolutionary approach and it has been evolving way back since OS 360, which came out in 1965. Since then, technology and even just the way people use technology has changed drastically and the new architectures have evolved to meet those demands such as Cloud services, Big Data analytics, mobile, and social computing, yet, there are programs written specifically for the original S 360 machines that are still running today, which is a testament to the goal of supporting backwards compatibility. Some of the major leaps forward for the platform include the addition of virtual storage in the system 370, 31 address bits and ESA and 64 bits in z where we are today. You may see mention of MVT, MVS, and OS 390. Those are all predecessors to the z/OS operating system, just like you may hear of 360, 370, z/900, z/9, z/10, z/196, z/13, and so on and so on. Those are all major mainframe families which predate the current generation and we are in the current generation. We'll try not to spend too much time going too far back in time because we're here. In the next module, we'll take a look at what makes a z/System a z/System.
