ZF Linux Devices Inc., Palo Alto, Calif., a small Silicon Valley chip designer, is expected to announce an alliance with chip maker National Semiconductor Corp. to create a Pentium-class personal computer the size of a matchbook. David Feldman, chief executive officer of the closely held ZF, said the company will begin selling its PC modules for embedded applications such as smart appliances or gas-stations pumps, in the fourth quarter. Each module will have three chips: a 166-megahertz or 133-megahertz Pentium class microprocessor, an eight-megabyte dynamic random-access memory chip for program storage and a flash chip for permanent storage. Mr. Feldman said the device will be used in everything from blood analyzers to gas pumps that can tell a visitor where the nearest restaurant or hotel is located.