Embedded Processor Watch

Editor: Tom Halfhill

In This Issue:

• SandCraft Adds Multimedia Extensions
• Another System On a Chip: IBM PowerPC 405GP
• Industry Resources: Intel Tells All at IDF
• New Embedded IC Announcements

SandCraft Adds Multimedia Extensions

Microprocessors without multimedia extensions are becoming as rare as unemployed engineers in Silicon Valley. Equally rare are embedded-processor companies that don't have a system on a chip (SOC) and "post-PC" strategy. One of the latest companies to swell the tide is SandCraft, which is introducing a new MIPS-compatible embedded CPU core with digital-signal-processing (DSP) and single-instruction, multiple-data (SIMD) extensions.

Although the new SR1-GX is compatible with the MIPS-IV instruction set, SandCraft is not a MIPS licensee. SandCraft's first customer for the core, LSI Logic, does have a MIPS license. LSI is integrating the SR1-GX in an SOC that a consumer-electronics company has commissioned for an advanced digital set-top box.

The SR1-GX is an enhanced version of the SR-1 core that SandCraft unveiled last fall (see Embedded Processor Watch #24, http://www.MDRonline.com/q/epw/issues/epw_24.html). It's a superscalar, out-of-order machine that can dispatch as many as four integer and two floating-point instructions per cycle. It has dynamic branch prediction and configurable L1 caches that can range in size from 8K to 64K. The caches can be direct mapped or two-, four-, or eight-way set-associative.

SandCraft says the customer originally wanted an embedded processor core that could run at 500-600 MHz to achieve the desired level of performance. Instead, SandCraft produced simulations to demonstrate that extensions to the SR1 core could deliver the same performance at 400 MHz while reducing costs and power requirements. SandCraft added an integer multiply-accumulate (MAC) unit, 16 new instructions for fixed-point DSP operations, a 64-bit FPU, 32 extra registers for single-precision floating-point numbers, and several new 32-bit SIMD instructions known as the Vector3D extensions.

Neither SandCraft nor LSI will reveal anything more about the customer, but the ability to run 3D video games appears to be a key part of the specification. It's unlikely that the customer is Nintendo, Sony, or Sega -- those companies have already settled on IBM, Toshiba, and Hitachi, respectively, to supply the CPUs for their next-generation game consoles. So until later this year, SandCraft's first design win for the SR1-GX will remain a mystery.

The SR1-GX doesn't come close to the performance of the Emotion Engine chip that Sony and Toshiba designed for the next-generation Sony PlayStation. The Emotion Engine (see Embedded Processor Watch #48, http://www.MDRonline.com/q/epw/issues/epw_48.html) can crunch 6.2 GFLOPS at 300 MHz -- almost four times the performance of the SR1-GX at a 25% slower clock speed. The Hitachi SH7750 in Sega's Dreamcast (see Embedded Processor Watch #2, http://www.MDRonline.com/q/epw/issues/epw2.html) can execute 1.2 GFLOPS at 167 MHz, which would scale to about 180% of the performance of the SR1-GX at a comparable clock frequency. Still, considering the SR1-GX's advantages in die size and power consumption, it acquits itself well in very fast company.--T.R.H. (The full version of this article appeared in the July 17 issue of Microprocessor Report.)

Another System On a Chip: IBM PowerPC 405GP

IBM's new PowerPC 405GP is by far the fastest, most highly integrated chip in the PowerPC 400 series. It's also a good advertisement for IBM's CoreConnect bus and Blue Logic macro library. (See Embedded Processor Watch #57, http://www.MDRonline.com/q/epw/issues/epw_57.html)

Other members of the PowerPC 400 family have no on-chip peripherals and stroll at clock frequencies of 25-80 MHz. The 405GP is a genuine system on a chip (SOC) that's loaded with useful peripherals. It's the first PowerPC chip based on the 405 core and will zip along at 200-266 MHz.

Unlike earlier 400-series cores, which have minimal three-stage pipelines to conserve every milliwatt of power, the 405 has a more conventional five-stage pipeline that can reach higher clock frequencies. It also has a 16K instruction cache, an 8K data cache, 4K of additional on-chip memory in the form of SRAM, and a function unit that executes 24 different multiply-accumulate (MAC) instructions -- a feature that no modern processor can do without, it seems.

The 405GP surrounds the 405 core with a wealth of on-chip peripherals, all joined together by the CoreConnect bus. In this implementation, the CoreConnect processor local bus is 64 bits wide and runs at 100 MHz -- half of the core's 200-MHz frequency. A second version of the chip will have a 133-MHz local bus and a 266-MHz core.

IBM designed the 405GP for Ethernet switches, low-cost routers, cable modems, network printers, base stations, remote-access devices, and similar applications. Its Ethernet port sets it apart from other embedded processors in this performance class that have a PCI bus and an SDRAM interface -- such as Hitachi's SuperH 7751 and Motorola's 8240. At $41, the 200-MHz 405GP is competitively priced with the 167-MHz SH7751 ($39) and the 200-MHz 8240 ($55).--T.R.H. (The full version of this article appeared in the July 17 issue of Microprocessor Report.)

Industry Resources: Intel Tells All at IDF

Get the latest word straight from the horse's mouth at the Intel Developer Forum. The fall edition will be held on August 31-September 2 at the Palm Springs (Calif.) Convention Center. The conference includes 13 technology tracks describing Intel's technology, including tracks on network processors and other embedded topics. Registration costs $995 for the three-day conference. For more information or to register, contact Intel at 888.266.7649 or click over to http://developer.intel.com/design/idf.

New Embedded IC Announcements

CS4928 (Cirrus Logic): A single-chip programmable DSP that supports both high-definition compatible digital (HDCD) and digital theater sound (DTS) standards for high-end automotive sound systems. Price: $15/10,000; production: now. Call Cirrus Logic at 510.623.8300 or go to http://www.cirrus.com/.

THS1206 (Texas Instruments): A 12-bit ADC with 16 words of on-chip FIFO memory and four sample-and-hold amplifiers; optimized for interfacing with a DSP for embedded applications. Price: $13/1,000; samples: now; production: 3Q99. Call TI at 800.477.8924 x4500 or go to http://www.ti.com/.

M16C/24 (Mitsubishi): A 16-bit USB 1.1 microcontroller for full-speed (up to 12 Mbit/s) peripherals; supports all USB transfer types (isochronous, bulk, control, and interrupt) with FIFO sizes of 32-128 bytes. Price: $5.30/10,000; samples: 3Q99; production: Q499. Call Mitsubishi at 408.730.5900 or go to http://www.mitsubishichips.com/.