Embedded Processor Watch

Editor: Jim Turley

In This Issue:

• Motorola PowerPC 8260 Begins Network Voyage

Motorola PowerPC 8260 Begins Network Voyage

Motorola's new MPC8260 (code-named Voyager) is the first of a line the company calls PowerQUICC II: PowerPC-based chips for the booming market in networking and telecommunications infrastructure. The 8260 is the biggest, fastest, most complex--and most costly--communications controller from the company so far. But Motorola hints that even more exotic controllers are on the way. The market's appetite for these chips seems insatiable: top names in telephones and networking such as Alcatel, Bay Networks, Lucent, Nokia, and Siemens have committed to use the MPC8260 in their equipment. The networking leader Cisco is also a rumored customer.

The 8260 is the first embedded controller to move up to the PowerPC 603e core; previous QUICC chips were based on the slower PowerPC 505 (see Microprocessor Report 5/9/94, p. 1). The 603e is two-way superscalar and runs at 100-200 MHz, delivering at least four times the performance of the 505 CPU.

The 8260 really has two internal microprocessors, the PowerPC EC603e and a proprietary communications processor module (CPM). The CPM is closely coupled with the chip's many serial channels and handles protocol conversion, packet stripping, CRC checking, and other low-level tasks. It executes its own library of microcoded functions under the direction of the PowerPC "host" processor. Users never program the CPM directly; commands and status are passed through the 24K of dual-ported SRAM that resides with the CPM.

The third significant change in the 8260 is the number and type of serial channels. The part has 13 independent serial ports of six different types. Starting from the fastest, most capable channels, Motorola calls these ports the fast (FCC), multichannel (MCC), and serial (SCC) communications channels, followed by the serial-management controller (SMC), the serial-peripheral interface (SPI), and the lowly inter-integrated circuit (I2C). Of this bewildering assortment of serial channels, the first two, MCC and FCC, are new to the 8260.

Motorola claims a total aggregate bandwidth of 710 Mbit/s, a somewhat useless statistic that nevertheless conveys the magnitude of the CPM's processing ability. More practically, the 8260 is equipped to handle one 155-Mbps ATM channel plus two 100-Mbps Ethernets, or 256 HDLC channels at 64 kbps, or just about any other serial protocol.

If the 8260 includes everything but the kitchen sink, how could Motorola extend the product line further? Pared-down versions are already in the works, which will backfill the price gap between the 860 and the 8260. To extend beyond today's high end, Motorola might add one of its fixed- point DSPs alongside the PowerPC and CPM processor cores; AltiVec extensions are another likely advance. DSP ability would go a long way toward enabling voice communication over the Internet. Voice-over-IP is being pursued eagerly by the networking companies (Cisco, et al) as they look to compete for voice traffic against nationalized and multinational telephone companies. If that effort shows signs of becoming a commercial success, the already fevered pace of the networking industry could heat up even more.