IBM details Power2+; DEC bares new Alpha AXP.

IBM details Power2+; DEC bares new Alpha AXP. (Alpha AXP 21164 microprocessor) (Product Announcement) (Electronic News)

STANFORD, CALIF.--IBM provided glimpses into its new Power2+ architecture- -which it claims offers the highest transaction processing speed of any processor in the industry-- and Digital Equipment Corp. (DEC) unveiled its new Alpha AXP 21164 implementation at the Hot Chips VI symposium at Stanford University, here, last week.

IBM did a technology trade-off in the Power2+ designed to leverage the Power2's architecture in order to reach new markets. "The primary project goals we had for the Power2+ project were that we really wanted to leverage off the original Power2 design and really went after two main areas, the first one being targeted transaction commercial processing. And the second was that we wanted to push the Power2 technology down to a lowercost, desktop-type machine," said David Shippy, an executive from IBM's RISC Systems/6000 Division, at Hot Chips.

In order to address these two markets with the Power2+, IBM reduced the data cache by half and the memory word interface from 8-word size to 4-word. The result is that performance is increased in low-end systems such as the RISC System/6000 (RS/6000) desktop computer system model 390, with a Power2+ chipset. The Power2+ model 390 features 67MHz clock operation and boasts SPECfp92 rating of 205.3; compared to the model 380 with a Power2 processor, that operates at clock speed of 59MHz and has a lower SPECfp92 rating of 187.2.

At the high-end, however, the Power2+ in the RS/6000 model R24 system operates at the same 71.5MHz clock speed as the Power2 in the model 990; and in terms of performance the model R24 actually drops behind the model 990 in SPECfp92 rating, with the model R24 system posting a SPECfp92 rating of 273.8 while the model 990 system reaches a slightly higher SPECfp92 rating of 279.

In the area of transaction processing, however, the Power2+ systems shine. In the model R24, the transactionsper-second rating (tpsA) is 357.2, nearly 80 basis points higher than the 275.6 tpsA rating in the model 990. This gives IBM just what it wanted--albeit achieved by performance tradeoffs--a chip suitable for both low-end PCs and high-end transaction processing systems. The device offers "the highest transaction processing performance level for any processor that's out there today," according to Mr. Shippy.

The Power2+ is manufactured using 0.7-micron process, four levels of metal and a level of polysilicon. The technology comes in a ceramic multichip module (MCM) package which includes four data cache chips, and a single solder balll connect (SBC) package for a cost-reduced chipset which includes two data cache units.

In terms of future developments, Mr. Shippy noted, "What you'll see with future technology is more of the core CPU--fixed point unit, floating point unit, will all be integrated onto a single chip and that'll help improve performance there, and the multichip module will help us package other high-speed interfaces onto the chip so it will scale to get to the really high-end performance."

Meanwhile, DEC unveiled its Alpha AXP 21164 successor to the 21064 anticipated since earlier this year (EN, April 25). The AXP 21164 is manufactured using 0.4-micron process and achieves 300MHz typical operating speed while using between 40 and 50 watts power. In order to overcome possible heat problems, "the device features a detachable heat sink that can even cool it in PC-type environments," according to Paul Rubinfeld of

DEC's Hudson, Mass, Semiconductor Engineering Group.

The AXP 21164 is a new design of the Alpha processor that features quad instruction issue, on-chip secondary cache and the ability to achieve a short latency at a high clock speed. In terms of enhancements over the previous generation 21064, the 21164 offers reduced key latencies such as wider integer multiply--a range of 19-23 compared to 8-16 for the 21064--four floating point cycles for the 21164 compared to six for the 21064, and two L1 data cache cycles compared to three cycles for the 21064.

DEC's new processor features performance specmarks of better than 1 SPECint92 per MHz, better than 1.5 SPECfp92 per MHz and better than 2 transactions-per-second per MHz, Mr. Rubinfeld said. Key features include 4-way issue superscalar architecture, on-chip L2 cache that provides at least three 32-byte blocks ahead of the current issue point, 7-stage integer pipeline, 9-stage floating point pipeline, emphasis on low latency at high clock rate and high throughput memory subsystem.

Other microprocessor developments at the symposium included other chip vendors offering additional insights into their most recent devices, such as Metaflow Technologies' 50MHz "Thunder" version of the Lightning SPARC chipset design--with 80MHz and 120Mhz versions on the way, and NEC's experimental 500MHz "Gallop" RISC processor--first discussed at the 1994 IEEE International Solid State Circuits Conference (ISSCC) in San Francisco earlier this year (EN, Feb. 21).

NEC recapped its Gallop 500MHz, 32-bit CMOS RISC processor first presented at ISSCC in February. The Gallop chip is an experimental design that features 0.4-micron CMOS 3-level aluminum design incorporating 201,478 transistors on a 7.9mm x 8.84mm chip. It uses a single 3.3- volt power supply and has a power dissipation rate of 6 watts at 500MHz.

"We had to solve several problems that the architecture and circuit design faced," said Kazumasa Suzuki of NEC's System ULSI Research Lab. Among the challenges were integrating high speed function blocks, and increasing speed while keeping voltage low. "The voltage load of the power supply makes the operation speed slow, and the noise caused by the chip operation resulted in errors." In order to overcome such problems, NEC has developed several techniques for increasing the speed of the MPU. Among the techniques: use of NEC's 3-level metal 0.4-micron process, as well as "development of high speed function blocks, design of a high-speed microprocessor architecture and integration techniques for the high-speed function blocks."

The Gallop chip architecture features 8-stage pipelined datapath, with simple datapath control--no pipeline hold and no register forearding, and on-chip test functions. High-speed circuit techniques include power and ground line structures that include up to 240 power lines, stageconnect clock distribution, high-speed input and output buffer circuit, and high-frequency PLL (phase locked loop) clockgenerator.

Bruce D. Lightner, co-founder and VP of development at Metaflow, a La Jolla, Calif. Design company, said the 50MHz Thunder SPARC processor is a new implementation of the 4-chip "Lightning" SPARC chipset that Metaflow developed for LSI Logic (completed in 1991 but never introduced). The Thunder project was 100 percent funded by Hyundai Electronics, a co-founder of Metaflow.

The 5-volt device incorporates 6 million transistors and features a patented out-of-order execution architecture that is said to eliminate processor stalls. Thunder consists of four chips: the integer unit, cache control/MMU/Bus Interface (CMB), Xcache RAM (1MB), and floating point unit.

Thunder is currently being manufactured by VLSI Technologies in a 391-pin IPGA package using both 0.6- and 0.8-micron process. In 4Q94, Metaflow will roll out a 80MHz version in a 600+ TBGA package, fabricated on 0.5-micron process. A 120MHz version, also on 0.5M process, is planned for 1995.

Mr. Lightner hinted at a foundry change by stating "I can't talk about our foundry partner today" for the planned 80MHz and 120MHz versions. In terms of performance goals, he said, "by the end of the year, we will achieve almost 200 SPECints and 400 SPECfp."

VADEM WINS BELLSOUTH DESIGN-IN

ORLANDO, FLA.--BellSouth last week announced availability of its "Simon" smart cellular phone that was designed by IBM and incorporates Vadem's VG-230 processor. When introducing Simon last year (EN, Nov. 8, 1993), BellSouth had not revealed the Vadem design-in.

The VG-230 is a 16MHz DOS-engine built around NEC's V30 CPU. Earlier this year, Vadem, San Jose, Calif., said it would upgrade its VG-230 to higher speeds; however, BellSouth is using the 16MHz device. Vadem won a big design-in with Sharp Electronics last year for the PT-9000 personal digital assistant. The V30 core is compatible with Intel' s 8086 microprocessor.

BellSouth said its Simon communicator has a pen for digital input, a PCMCIA slot, a 9.6K bit/sec. fax/modem and a series of menus for address books and phone numbers. It is priced at about $900.

DeTar, Jim, IBM details Power2+; DEC bares new Alpha AXP. (Alpha AXP 21164 microprocessor) (Product Announcement)., Vol. 40, Electronic News, 08-22-1994, pp 2(2).