TOKYO, OCT. 15 -- The president of a big electronics company held a press conference in a lavish Tokyo hotel ballroom today to announce a new microchip that is likely to be a huge seller here. The event would be fairly standard industrial fare, except the firm making that big splash in Japan today was an American company.

Intel Corp., a Santa Clara, Calif.-based maker of microprocessor chips, at the heart of a computer's processing power, came to Tokyo to announce its new 80386SL chip, a tiny powerhouse that should permit clear improvements in the next generation of portable and laptop personal computers.

Intel President Andrew Grove said he chose to make the announcement in Japan because so many important makers of laptop PCs are here. All those Japanese firms -- including Toshiba Corp., NEC Corp., Sharp Corp. and Panasonic Co. -- are dependent on Intel's technology for the microprocessor chip that is the sine qua non of every successful portable computer.

The arrival of the 80386SL, and the enormous interest it has garnered here, demonstrates how powerful the United States continues to be in modern microchip development.

While politicians and academics regularly bemoan the fact that the United States has lost its erstwhile lead in computer memory chips, American makers still dominate the market for the microprocessor, a product that is harder to make but far more profitable than a memory chip.

Memory chips store information and retrieve it at high speed. The chips have a repetitive design that looks like a tennis net. In large quantities, big memory chips sell for about $5 each and carry small profit margins.

A microprocessor acts as the central switchboard controlling all parts of a computer, and also contains much of its computational capabilities. Viewed through a microscope, a microprocessor looks like an immensely complex city map. This intricate design keeps prices high -- above $150 for state-of-the-art chips -- and helps assure high margins.

Several Japanese firms produce microprocessors of their own design, but each one has a minute market share compared with the two American giants, Intel and Motorola Inc.

The new microprocessor announced today will provide the full speed and power of Intel's current 80386 chip but in an unusually tight package. That should mean a new generation of laptop machines that can run Microsoft Windows software in color but still weigh less than current laptops and use lighter batteries. Intel said prices should be "competitive" with current machines using the 80386SX chip.

So many functions have been jammed onto the new chip -- its circuitry contains about 855,000 transistors, all packed onto a razor-thin silicon wafer about the size of a fingernail -- that the number of supporting chips surrounding the microprocessor can be drastically reduced in making a computer.

Intel engineers say the new chip eventually should permit production of lighter and smaller laptop PCs.