Out in Front: March 28, 1996

Although OEMs have long used Sun’s SPARC processor in embedded applications, Sun itself has only recently begun to seriously focus on that market, particularly for networking, telecommunications, and high-end printers and copiers. Emphasizing that focus, the company has spun off Sun Microelectronics, which has recently introduced its first product, the microSPARC IIe, a derivative of the microSPARC II. Although the basic architecture of the two designs remains the same, Sun redesigned the IIe modularly to make it easier to build future implementations targeting specific applications.

To help the IIe fit better into embedded applications, Sun made a few important changes, including using a new process technology yielding a smaller die. Also, because few embedded applications use floating-point arithmetic, Sun retained the microSPARC’s microcoded control floating-point unit but removed the higher performance, real-estate-hungry, hard-wired multiplier. The IIe also has more enhanced power-down circuitry than its workstation counterpart.

The IIe has several features that improve its system-level interface, including an integrated "custom" PCI bus interface that allows the controller to act as both a master and a target PCI device. Sun offers a gate array that bridges the IIe to the system’s PCI bus. The IIe still retains its 25-MHz SBus interface to allow customers to support legacy devices. Eventually, Sun will phase out the SBus interface, because most new systems are moving to the 33-MHz PCI bus.

The IIe still uses a 64-bit, fast-page-mode DRAM interface. Future implementations of the device will support a selectable 32- or 64-bit-wide DRAM bus. The IIe also incorporates a 32-bit-wide flash-memory/ROM interface. The flash interface supports software-programmable latency of 50 to 450 nsec, in-circuit reprogrammability, and "cacheable" accesses. Using a pin selector, your system can boot from flash memory or through the SBus.

Sun designers packed the IIe into a 361-lead ceramic ball-grid-array package, and price is approximately $150. The core of the device operates at 3.3V and has 5V-tolerant I/O. The IIe has a peak power rating of 7W at 125 MHz. Sun offers a reference board that includes an SBus slot, as many as four PCI-bus slots, a parallel interface, serial channels, an interrupt controller, and several other system-level features.
—by Markus Levy

Sun Microelectronics, Mountain View, CA. (408) 960-1300.