Robert M. Averill

IBM's S/390 G5 microprocessor design

The IBM S/390 G5 microprocessor in IBMs newest CMOS mainframe system provides more than twice the performance of the previous generation, the G4. The G5 system offers improved reliability and availability, along with new architectural features such as support for IEEE floating-point arithmetic and a redesigned L2 cache and processor interconnect. The G5 system implements the ESA/390 instruction-set architecture, which is based on and compatible with the original S/360 architecture. Therefore, it has no RISC (reduced-instruction-set computing) concepts and is one of the most complex of all CISC (complex-instruction-set computing) architectures. Designers had to meet a unique set of challenges to achieve the G5s level of performance-for example, achieving a very high frequency given the complexity of the architecture.

IBM POWER6 microprocessor physical design and design methodology

The IBM POWER6™ microprocessor is a 790 million-transistor chip that runs at a clock frequency of greater than 4 GHz. The complexity and size of the POWER6 microprocessor, together with its high operating frequency, present a number of significant challenges. This paper describes the physical design and design methodology of the POWER6 processor. Emphasis is placed on aspects of the design methodology, technology, clock distribution, integration, chip analysis, power and performance, random logic macro (RLM), and design data management processes that enabled the design to be completed and the project goals to be met.

A radix-8 CMOS S/390 multiplier

The multiplier of a S/390 CMOS microprocessor is described. It is implemented in an aggressive static CMOS technology with a 0.20-/spl mu/m effective channel length. The multiplier has been demonstrated in a single-image shared-memory multiprocessor at frequencies up to 400 MHz. The multiplier requires three machine cycles for a total latency of 7.5 ns, though the design can support a latency of 4.0 ns if the latches are removed. The design goal was to implement a versatile S/980 multiplier with reasonable performance at a very aggressive cycle time. The multiplier implements a radix-8 Booth algorithm and is capable of supporting S/390 floating-point and fixed-point multiplications, and also divisions and square roots. Logic design and physical design issues are discussed relating to the Booth decoding and counter tree implementations.

A 5.2GHz microprocessor chip for the IBM zEnterprise™ system

The microprocessor chip for the IBM zEnterprise 196 (z 196) system is a high-frequency, high-performance design that adds support for out-of-order instruction execution and increases operating frequency by almost 20% compared to the previous 65nm design, while still fitting within the same power envelope. Despite the many difficult engineering hurdles to be overcome, the design team was able to achieve a product frequency of 5.2GHz, providing a significant performance boost for the new system.

760 MHz G6 S/390 microprocessor exploiting multiple Vt and copper interconnects

The G6 system is a sixth generation CMOS server for the S/390 line of products featuring a 12+2 SMP size and significant frequency improvements obtained through the use of low-Vt devices and copper interconnects. The microprocessor operates at 760 MHz at the fast end of the process distribution. The system ships at 637 MHz in a 12+2 chilled SMP configuration. Measured system performance on the 12 way is 1600 S/390 MIPs, providing over 50% more performance than the G5. This microprocessor uses CMOS7S technology, which has a 0.2 /spl mu/m process. The chip uses 6 levels of copper metal plus an additional layer of local interconnect on a 14.6/spl times/14.7 mm/sup 2/ die with 25M transistors (7M logic/18M array). The power supply is 1.9 V and the chip power is 33 W at 637 MHz.

609 MHz G5 S/399 microprocessor

The IBM G5 system is a fifth-generation CMOS server for the S/390 line of products with functionality improvements such as an instruction branch target buffer (BTB) and an IEEE compliant binary floating-point. The microprocessor operates at 600 MHz at the fast end of the process distribution, although the system is shipped at 500 MHz in a 10+2 SMP configuration. Measured system performance on the 10 way is 1069 S/390 MIPs. This microprocessor uses a 0.25 mum CMOS process. The chip uses 6 levels of metal plus an additional layer of local interconnect and is 14.6times14.7 mm2 with 25 M transistors (7 M logic/18 M array). Power supply is 1.9 V. Chip power is 25 W at 500 MHz

Deep submicron design techniques for the 500 MHz IBM S/390 G5 custom microprocessor

High frequency microprocessor designs require rigorous design guidelines, design methodology advancements, and novel approaches in circuit design style for processors operating in the high megahertz range. Timing closure becomes the single most important design issue, however other design metrics such as area, power and noise need to be given equal consideration within the design cycle. Custom design techniques were used through out the logic circuits and arrays as well as the overall design planning for the 500 MHz microprocessor cycle time.