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UltraSPARC: Coming soon

Sun's CPU catches up (at last) to its competitors

By David Burnette

July  1995
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Long the performance laggard in the CPU foot-race, Sun's UltraSPARC processor promises to gain a lap or two on the competition. With an expected performance of 275 SPECint92 and 350 SPECfp92 Sun hopes to change its reputation for lackluster CPU horsepower. Sun is not alone on the UltraSPARC bandwagon. Upwards of twelve computer vendors have pledged to deploy systems fired by the new processor.

Systems using the UltraSPARC chip set are due late this year.

The design of the UltraSPARC processor is worthy of some discussion. UltraSPARC is not contained within one integrated circuit package; it comprises several chips. This assemblage is the UltraSPARC processor. A specific subset of these chips is referred to as the chip set.

[UltraSPARC chip GIF, 72K]The chip set consists of the uniprocessor system controller (UPC), the UPA-to-SBus interface (U2S), the reset/interrupt/clock controller (RIC), and the crossbar switch. For the EE-wannabes in the audience, the UPC regulates the flow of requests and data throughout the processor, the U2S serves as the primary connection between the system bus and the I/O subsystem (SBus), the RIC supports the system resets, interrupts, scan, and clock-control functions. Finally, the crossbar switch is the bridge between three different data buses: processor, memory, and I/O.

AT&T makes the SC, RIC, and U2S. Texas Instruments fabricates the crossbar switch. Beginning in the fall, Sun will sell this set for $450 in quantities of a thousand. Sound inexpensive? There's more to the UltraSPARC processor than the chip set. Other crucial components are necessary, namely the CPU complex, which consists of the CPU itself, cache, and other support chips. Sun prices the 167-MHz version of this at $1,595 for quantities of a thousand; the 143-MHz version is $1,095. Additional piddling chips bring the total price tag for a complete 167-MHz UltraSPARC implementation to around $2,000.

Bells and whistles
Sun stresses the UltraSPARC's multimedia processing capabilities, saying that it's the first processor to deliver the compute power and throughput necessary for advance graphics and real-time video applications. To do this, the processor sports a visual instruction set (VIS). VIS provides hardware support for 2-D and 3-D graphics operations, video processing, and image compression and decompression. According to Sun, this specialized horde of instructions, coupled with the UltraSPARC's high bandwidth, enables the processor to support video animation for a 1000x1000 screen at a refresh rate of 30 frames per second with bandwidth to spare.

In addition to the multimedia features, VIS supports two important requirements for public networking: encryption and error correction. High-speed graphics operations can be used by encryption algorithms to safeguard data destined for insecure nets. Check-summing and signature-generation algorithms, also utilizing VIS, ensure data sent over a network is data that arrives.

Lest you think this strays too far from RISC philosophy, only 3 percent of the chip real estate is devoted to these fancy graphics instructions.


Tortoise and the Hare
The first UltraSPARC systems are due out from Sun and others by the end of the year. Sun has broken with tradition by not withholding system components from partners, enabling other vendors to simultaneously ship systems equivalent in performance to Sun's.

Ultrasparc will mean catchup time for Sun; briefly it may even be the fastest chip around, though rivals, such as the MIPS R10000 and HP's PA-8000, are expected to leapfrog it quickly (in terms of SPECmarks anyway; other performance areas aren't as clear). Nevertheless, the real achievement for Sun will be to finally, after the long disappointment with the performance of SuperSPARC, be back in the game.

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