ON SEMICONDUCTOR to acquire CATALYST SEMICONDUCTOR in an all-stock transaction

PHOENIX, AZ and SANTA CLARA, CA – July 17, 2008 --ON Semiconductor Corporation (Nasdaq: ONNN) and Catalyst Semiconductor, Inc. (Nasdaq: CATS) today announced the signing of a definitive merger agreement providing for the acquisition of Catalyst Semiconductor by ON Semiconductor in an all-stock transaction in which Catalyst shareholders will receive 0.706 shares of ON Semiconductor common stock for each share of Catalyst common stock they own. This represents an equity value of approximately $115 million and an enterprise value of approximately $85 million.

“The acquisition of Catalyst Semiconductor will add to our high gross margin analog and mixed-signal product offerings for the digital consumer and wireless end-markets,” said Keith Jackson, ON Semiconductor president and CEO. “Catalyst Semiconductor’s analog and mixed-signal business represented more than $11 million in sales as of their April 2008 fiscal year end - a business that grew more than 90 percent versus the prior year. Catalyst Semiconductor’s EEPROM technology will strengthen our custom application-specific circuits (ASIC) and power products capabilities expanding our ability to more comprehensively address our customers’ needs. With the combination of ON Semiconductor's global footprint, effective channels of distribution, and top-tier customer relationships, we expect to be able to support a broader and deeper penetration of Catalyst's overall product portfolio. This should enable us to accelerate their revenue growth and increase market share. We also believe additional revenue from Catalyst Semiconductor’s strong portfolio offering will benefit from ON Semiconductor’s manufacturing capabilities. We look forward to welcoming Gelu Voicu, Catalyst Semiconductor’s CEO, as well as the talented Catalyst employee base to ON Semiconductor.”

“This transaction represents a compelling opportunity for Catalyst employees, customers and shareholders,” stated Gelu Voicu, CEO of Catalyst Semiconductor. “To compete successfully in today’s global marketplace, size and scale are very important. We are pleased to become part of a leading global company in the semiconductor sector. ON Semiconductor’s world-class operational capabilities and supply chain will enable Catalyst Semiconductor’s products to better penetrate the automotive, consumer, and industrial end-markets utilizing ON Semiconductor’s global customer and channel footprint.“

The transaction is subject to the approval of shareholders of Catalyst Semiconductor as well as customary closing conditions and regulatory approvals. The companies expect the transaction to close in the fourth quarter of 2008. Upon closing, ON Semiconductor may record a one-time charge for purchased in-process research and development expenses and other deal related costs. The amount of that charge, if any, has not yet been determined.

“This acquisition is directly aligned with both our strategic and financial goals,” said Donald Colvin, ON Semiconductor executive vice president and CFO. “Net of cash and short term investments of approximately $30 million at the end of April 2008, the transaction value represents approximately 1.1 times trailing twelve month sales. We also believe ON Semiconductor’s operational strengths will significantly benefit the revenue and margin potential of Catalyst Semiconductor. Excluding the impact of amortization expense, write-up of inventory to fair market value, one-time and other deal related charges discussed above, we expect the acquisition will have minimal impact to earnings per share in the first year post the transaction close and should be accretive to our earnings per share thereafter. ON Semiconductor’s business and the integration of AMIS Holdings, Inc. has proceeded as anticipated and we are comfortable with the guidance and current level of revenue and earnings expectations provided on our May 5, 2008 conference call. We intend to provide further details on the acquisition and our second quarter 2008 results on our regularly scheduled quarterly earnings conference call on Aug. 6, 2008.”

About ON Semiconductor

With its global logistics network and strong product portfolio, ON Semiconductor (NASDAQ: ONNN) is a preferred supplier of high performance energy efficient silicon solutions to customers in the power supply, automotive, communication, computer, consumer, medical, industrial, mobile phone, and military/aerospace markets. The company’s broad portfolio includes power, signal management, analog, DSP, advance logic, clock management and standard component devices. Global corporate headquarters are located in Phoenix, Arizona. The company operates a network of manufacturing facilities, sales offices and design centers in key markets throughout North America, Europe, and the Asia Pacific regions. For more information, visit http://www.onsemi.com.

About Catalyst Semiconductor

Headquartered in Santa Clara, California, Catalyst Semiconductor designs and markets analog, mixed-signal and non-volatile memory products, including Digitally Programmable Potentiometers (DPP™), white and color LED drivers, DC/DC converters, LDO regulators, voltage supervisors, bus expanders, serial and parallel EEPROMs, Flash and NVRAM. Many of Catalyst’s products incorporate the Company’s Quantum Charge Programmable™ technology, to deliver Adaptive Analog™ products, which offer a new level of customer flexibility, lower power and smaller die size. Catalyst products are used in telecommunications, computer, automotive, industrial and consumer markets. Typical applications include LCD displays, automotive lighting, optical networks, printers, modems, wireless LANs, network cards, DIMM modules, cellular telephones, navigation systems, set-top boxes and Internet routers.