Alexis Tannenbaum
What do you want from a notebook chip set? Texas Instruments is betting that it's PCI (Peripheral Component Interconnect) bus speed combined with 3.3-V, clock-doubled 486 power and extremely low power consumption. TI says Rio Grande-based notebook PCs should start appearing this fall.
At the heart of the Rio Grande is a TI486 CPU that comes in external/internal clock-speed versions of either 25/50 MHz or 33/66 MHz. Because it's on the same silicon as the CPU, the integrated memory controller allows memory accesses at the chip's full internal speed.
Unlike Intel's 486SL chip family, which integrates an ISA bus controller, the Rio Grande integrates a PCI controller. By placing this controller on the same low-powered chip as the CPU, TI enables manufa
cturers to bring local-bus, high-bandwidth devices, such as high-performance IDE drives, to laptops and notebooks.
Like the 486SX, the Rio Grande does not include an FPU, although it has an FPU interface. TI also includes a PCMCIA bus controller on the chip, which manages two PCMCIA slots and bridges the gap between the PCMCIA bus and the PCI bus with a four-level, 32-bit buffer.
Linley Gwennap, editor in chief of the Microprocessor Report (Sebastopol, CA), says that a potential benefit of the Rio Grande to system makers is that the chip's projected cost premium of approximately 20 percent over a 486DX chip is much better than the 80 percent higher manufacturing cost incurred by Intel in its now-discontinued 486SL line of processors.
Illustration: TI packs many devices into its Rio Grande chip set, but perhaps the most intriguing is the Power Management Unit (PMU) interface. TI says its 486 can turn off and on between keystrokes by switching the CPU off and on in 2 percent of the time
required by rival active power management systems. TI hopes this feature will double a notebook PC's battery life.
TI Charges into the Notebook CPU Wars
