The IBM z13i system is the latest generation of the IBM z Systemsi mainframes. The z13 microprocessor improves upon the IBM zEnterprise A EC12 (zEC12) processor with two vector execution units, higher instruction execution parallelism, and a simultaneous multithreaded (SMT) architecture that supports concurrent execution of two threads. These advances yield performance gains in legacy online transaction processing and business analytics workloads. This latest generation system features an eight-core processor chip, a robust cache hierarchy, and large multiprocessor system design optimized for enterprise database and transaction processing workloads. The microprocessor core features a wide super-scalar, out-of-order pipeline that can sustain an instruction fetch, decode, dispatch, and completion rate of six z/Architecture A instructions per cycle. The instruction execution path is predicted by multi-level branch direction and target prediction logic. Complex instructions are split into two or more simpler micro-operations. Instructions are issued out of program order from an instruction issue queue to multiple RISC (reduced instruction set computer) execution units. The super-scalar design can sustain an issue and execution rate of ten micro-operations per cycle: two load/store type instructions, four fixed point (integer) instructions, two floating point or vector instructions, and two branch instructions.

Formal verification (FV) is considered by manyto be complicated and to require considerable mathematical knowledge for successful application. We have developed a methodology in which we have added formal verification to the verification process without requiring any knowledge of formal verification languages. We use only finite-state machine notation, which is familiar and intuitive to designers. Another problem associated with formal verification is state-space explosion. If that occurs, no result is returned; our method switches to random simulation after one hour without results, and no effort is lost. We have compared FV against random simulation with respect to development time, and our results indicate that FV is at least as fast as random simulation. FV is superior in terms of verification quality, however, because it is exhaustive.

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The performance of large servers is to a high degree determined by their I/O subsystems. In the z990 server, nearly all of the components in the I/O path have been considerably improved in performance, capability, and cost. A 2-GB/s enhanced self-timed interface (eSTI) was introduced which is capable of absorbing the ever-increasing data rates of modern high-speed adapters. The I/O bandwidth available from a single node (three memory bus adapter, or MBA, chips, each with four eSTI ports) now equals 48 GB/s. As a consequence, both the MBA chip and the STI multiplexer switch (STI switch) chip had to be completely redesigned. In addition to these two chips, this paper describes the eSTI design itself and the Sweep chip, which integrates the function of four bidirectional adapter chips, one switch chip, and a clock chip.

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